Repair Corrupted Flash Drive on Mac and Recover Data

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Step 1: Check Disk Utility for Drive Visibility

The first step is to confirm whether your Mac recognizes the drive. Even if it doesn’t appear in Finder, Disk Utility can help determine if the drive is at least detectable. Disk Utility displays all storage devices connected to your Mac, making it a quick and easy way to check the drive’s status.

1. Open Disk Utility. Go to Applications > Utilities > Disk Utility to get started.

   

2. Look for your flash drive under External in the sidebar. If you see it here, it means your Mac recognizes the drive, even if you can’t fully access it.

3. If the drive shows up but isn’t mounted, select it and click Mount at the top of the window. This tries to make the drive accessible in Finder, which might let you open and access files.

   

4. Take note of any error messages. Disk Utility may show an error if it can’t mount the drive. This feedback could be useful as you move through the next steps.

If the drive doesn’t appear in Disk Utility, try these steps: connect it directly to your Mac instead of through a USB hub, use a different USB port, or, if possible, test the drive on another Mac. If it still doesn’t show up, the issue is likely physical damage or severe corruption. In such cases, DIY methods won’t help, and professional data recovery may be your best option.

Step 2: Backup Your Files from the Drive to Your Mac

Before attempting any repairs, back up any files you can still access. Some repair steps could compromise your data, so creating a backup ensures your files remain safe.

But what if the drive isn’t accessible in Finder, or doesn’t appear at all? Specialized data recovery software can often retrieve files even from corrupted USB drives.

There are many data recovery apps online, but not all are reliable. Here’s what to look for in a tool suited for your situation:Pick a tool that can handle the file systems you typically see on USB drives, like FAT32, exFAT, NTFS, and APFS. This way, it can read your data, no matter the drive’s format.

• A good recovery app offers a few types of scans, each aimed at different issues:

  • Quick Scan: Fast and useful for recently deleted files or minor problems, but it’s not very thorough.

  • Deep Scan: Digs into the drive to find files on more seriously damaged or corrupted drives; this one takes more time but gets more results.

  • Signature Scan: Ignores the file system and searches by file type (like JPEGs or PDFs), which works well when the file system itself is too damaged.

• Look for a tool that can create a disk image of your USB drive. This lets you work from a copy instead of the original drive, which lowers the risk of more damage while you recover data.

• Make sure the software works with macOS, especially the latest versions like Sonoma and Sequoia. Lots of recovery apps online haven’t been updated in years, so check that it’s built for your Mac’s OS.

With these points in mind, a couple of tools stand out: Disk Drill and UFS Explorer. You can check out these and other options in our list of the best data recovery apps for Mac. Personally, we’d go with Disk Drill—it consistently gets great recovery results, and unlike UFS Explorer, it’s super easy to use, so anyone can jump in without any hassle.

How to Create a Backup Image of Your Corrupted USB Drive

The Backup feature in Disk Drill, called Byte-to-Byte Backup, creates a complete image of your USB drive. This image includes everything—existing files, damaged files, deleted files, and any data left on the drive.

You’ll need enough free space on your Mac’s drive or another external drive to save this backup image. In fact, you’ll need slightly more than the full size of your USB drive, not just the size of the used space, since the backup file captures everything on the drive.

Here’s how to create a backup image with Disk Drill:

1. Go to Disk Drill’s official website, download the app, and install it on your Mac. The free version lets you preview recoverable files, which can be helpful if you’re evaluating your recovery options.

2. Launch Disk Drill and plug in your corrupted USB drive. Even if Finder doesn’t recognize the drive, Disk Drill should still detect it as long as it’s connected to your Mac.

   

3. In Disk Drill, find your USB drive in the list of devices. Select it, then click on Byte-to-Byte Backup.

4. Disk Drill will prompt you to choose a location for the backup image. Pick a safe spot on your Mac’s internal storage or an external drive.

5. Click Create backup to start.

   

6. After the backup is complete, go back to Disk Drill’s main screen (click on to return). Select Attach disk image, choose your backup file, and mount it in Disk Drill. Now, you can scan and recover data from the image itself, without touching the original drive.

Note. Disk Drill has three versions to suit different recovery needs:

• Free version – Lets you scan and preview recoverable files, so you can see what you might be able to get back, but limits actual recovery capabilities.

• Pro version – Costs $89 and offers unlimited data recovery. It’s ideal for personal use when you need full recovery access.

• Enterprise version – Priced at $499, this version includes unlimited data recovery for up to 10 users, with priority tech support. It’s a great choice for businesses and IT pros.

How to Recover Files from the Backup Image

Now that you have this backup image, no matter what happens next, you’ll be able to recover files from it just as they were when you created it. It’s like having a snapshot of your USB drive at that moment. You could go ahead and scan the original drive itself—maybe things aren’t as bad as they seem—but we can’t know that for sure. That’s why we always recommend to make a backup and scan it instead. Just to be safe.

Here’s how to go through the recovery process from here:

1. Now that you see your created disk image in Disk Drill’s main screen, click on Scan for Lost Data. This will start the process.

   

2. Click on Search for lost data. Disk Drill will automatically run Quick, Deep, and Signature Scans in sequence to maximize your chances of finding lost files.

3. Once the scan completes, click Retrieve found items at the top of the interface.

   

4. You’ll see a list of files categorized into groups: Existing files (these are the files that should be fully intact on the backup image), Deleted or lost (includes files you deleted in the past but that haven’t been fully overwritten yet. Disk Drill can recover them if they’re still there in part or whole), and Reconstructed (Disk Drill attempts to rebuild these files if the structure is too damaged).

   

5. You’ll see Recovery chances next to each file with tags like High, Average, or Low.

6. You can pick and choose what you want to retrieve, or simply select everything.

7. Click Recover, then select a safe destination for the recovered files.

Step 3: Use First Aid to Repair the Flash Drive on Your Mac

Once you’ve backed up and recovered any important files, it’s time to attempt repairs on the USB drive itself. Disk Utility’s First Aid tool can detect and fix basic file system errors, making it the first repair option to try for a corrupted drive on macOS.

Note: Sometimes running First Aid more than once helps. The tool may miss or only partially fix certain issues on the first pass.

Here’s how to run First Aid to repair a corrupted flash drive on a Mac:

1. In the sidebar under External, find and select your USB drive. Double-check that you’ve chosen the correct drive to avoid any accidental repairs on other devices.

2. At the top of the Disk Utility window, click First Aid. A prompt will pop up explaining that First Aid will scan for errors and attempt to fix them.

   

3. Click Run to start. Disk Utility will scan the drive for any errors. You’ll see a progress bar, and Disk Utility will notify you if it finds any problems and whether it can fix them.

Once the scan is complete, Disk Utility will display a message with the results. If it found and fixed issues, try accessing your USB drive in Finder to see if it’s working properly.

If First Aid can’t repair the drive, the problem may be more serious—like severe file system corruption or hardware failure. In that case, more advanced repair options are needed.

Step 4: Use Terminal to Repair the USB Drive on Your Mac

If Disk Utility’s First Aid didn’t solve the issue, Terminal provides a more advanced method for troubleshooting. Terminal commands can sometimes fix problems that Disk Utility cannot handle. In this step, we’ll cover two options: using the repairVolume command for basic repairs, and TestDisk for more complex partition issues.

Option A: Repair USB Drive on Mac using Terminal Commands

Terminal is macOS’s command-line tool that allows direct interaction with the system. While it may seem technical at first, it’s straightforward once you get the hang of it and can handle problems standard tools might miss.

Here’s how to open Terminal and use it to repair your USB drive:

1. To open Terminal, go to Applications > Utilities > Terminal. You can also open it quickly with Spotlight Search (press Command + Space, type “Terminal”).

   

2. Terminal lets you run specific commands to make changes directly to the system. You type a command, press Enter, and Terminal runs that command. First, type diskutil list and press Enter to execute it.

3. This command shows all connected drives and their identifiers (like /dev/disk2). Look for your USB drive by name, size, or details, and note its identifier.

   

4. Once you’ve identified your USB drive, type the following command (replace diskX with your USB drive’s identifier), then press Enter:
   sudo diskutil repairVolume /dev/diskX

   

5. You may be prompted to enter your Mac’s admin password. Terminal will try to repair the drive and show you updates as it works. If it finds and fixes errors, it will let you know.

After the repair, open Finder and check if your USB drive is now accessible. If the repair worked, you should see your drive and be able to use it.

Note. We’ve seen cases where the problem wasn’t with the USB drive itself but with the way macOS manages USB connections. You can restart the USB daemon, which handles USB device connections, to fix this issue. To do this, open Terminal and type sudo launchctl stop com.apple.usbd, then press Enter.

Next, type sudo launchctl start com.apple.usbd and press Enter again. Unplug your USB drive, wait a few seconds, then plug it back in to see if it’s recognized.

Option B: Repair USB Drive Partition Issues with TestDisk on Mac

TestDisk is a free, open-source tool designed to recover lost partitions and fix file system issues, especially in cases where viruses or human error (like accidentally deleting a partition table) have caused problems. While TestDisk is powerful, it’s not the easiest tool to use—it only works through the command line in Terminal, so there’s no graphical interface. But for complex cases that regular repair tools can’t handle, TestDisk can work wonders.

Here’s how to use TestDisk to fix an unreadable USB flash drive on a Mac:

1. Head to the TestDisk website to download the Mac version, and follow the site’s instructions to install it on your Mac.

2. Open Terminal, navigate to where TestDisk is installed (for example cd ~/Desktop/testdisk-7.2
   ), and type:
   sudo ./testdisk

3. Press Enter, and enter your admin password if prompted to start TestDisk with the necessary permissions.

4. TestDisk will show a list of drives connected to your Mac. Use the arrow keys to highlight your USB drive, then choose Proceed.

   

5. TestDisk usually detects the partition table type automatically. If you’re unsure, the default option should work. Confirm the detected type and press Enter.

   

6. Follow the prompts to Analyze the drive; this scan checks for any lost or damaged partitions.

   

7. After that, TestDisk will show options for recovering or repairing partitions based on what it found. Carefully follow the instructions to restore lost partitions or repair the file structure. Since it’s all command-line based, take your time to make sure you select the right options for your situation.

Once you’ve finished using TestDisk, open Finder to check if your USB drive is now accessible. If TestDisk successfully repaired the drive, it should appear and be ready to use.

Step 5: Nothing Worked? Format the USB Drive

If all else fails and the flash drive is still problematic, formatting is usually the last and most effective solution for non-physical issues. Formatting completely erases all data and creates a new file system, giving the drive a fresh start. You’ll use Disk Utility for this step, which you’re already familiar with.

Important: Formatting will wipe everything on the drive, so ensure you’ve recovered any important files beforehand. If you forget something, you can sometimes still recover data after formatting using Disk Drill, depending on the type of format applied.

Here’s how to format your USB drive on a Mac:

1. In Disk Utility, locate and select your USB drive.

2. At the top of the Disk Utility window, click Erase. A dialog box will appear where you can rename the drive and choose a format.

   

3. Choose a Format and type a name for the drive in the Name field to make it easier to identify later.

   

4. Click Erase to start formatting. Disk Utility will erase everything, set up a new file system, and remount the drive once it’s done.

What format to choose?

• exFAT: Works on both macOS and Windows; is a good choice if you use the drive on different systems.

• Mac OS Extended (Journaled): Best if you’ll only use the drive on Mac.

• APFS: Great for newer Macs but not compatible with older versions of macOS.

Once Disk Utility finishes, open Finder to check if your USB drive is now accessible.

Parting Advice

These five steps fix USB issues for roughly 9 out of 10 drives, but some drives are simply too damaged for at-home methods or standard tools. If your USB contains very important data and none of these steps worked, the safest option is to contact a professional data recovery service.

Professional services have specialized equipment and techniques to handle severe damage, including physical repairs to the drive’s components and advanced methods to extract data. Recovery from a USB drive can be expensive—often costing more than a new drive—but if the data is irreplaceable, professional recovery is usually the last, and sometimes only, solution.