How to Recover Files From a Corrupted USB Drive in Windows

A damaged USB drive can turn a normal afternoon into a small panic. The drive may appear empty, Windows may ask to format it, or familiar folders may suddenly be replaced by files with a .CHK extension.

The most important thing is to slow down. Every write to a damaged drive can overwrite something you still want to recover. Do not format it, save new files to it, or install recovery software on it.

This is the order I would use at a repair bench. Start with the least invasive checks and move toward repair only after the readable data is safe.

Before repairing anything

If the USB drive opens and any files are readable, copy those files to your computer or another healthy drive first. Copy them. Do not move them.

If the data is irreplaceable, the drive disconnects while you use it, reports the wrong capacity, gets unusually hot, or is physically damaged, stop here. Repeated scans can make a failing device worse. A professional recovery service is the safer choice for valuable data.

For less critical files, recovery tools can also work from a disk image instead of the original device. The TestDisk documentation explains how its tools can read image files. Imaging first is the better option when you have the equipment and storage space.

1. Confirm the drive letter

Plug in the USB drive and open File Explorer. Look under This PC and note the drive letter. I will use G: in the examples below, but yours may be different.

Double-check the letter before running any command. Repairing the wrong drive is an avoidable bad day.

⚠️ Replace G: with your USB drive letter in every command below.

2. Check the file system without changing it

Open Command Prompt as Administrator:

1. Open Start and type cmd.
2. Right-click Command Prompt.
3. Select Run as administrator.

Start with a read-only check:

chkdsk G:

Without a repair option, CHKDSK reports the file-system status but does not fix errors. Read the result before moving on.

3. Repair logical file-system errors

Once readable files have been copied somewhere safe, run:

chkdsk G: /f

The /f option tells Windows to repair logical file-system errors. This changes data structures on the USB drive, which is why the backup step comes first.

What to look for:

• Windows has made corrections to the file system means CHKDSK repaired one or more errors.
• Cannot open volume for direct access means another program, a security tool, or a failing connection may have control of the drive.
• A repeated bad-sector warning points to failing storage. Recover your files and replace the drive.

Microsoft documents the available options in its CHKDSK command reference. The /r option also looks for bad sectors and attempts to recover readable information, but it takes longer and puts more load on the device. I would not start with /r on a drive that may be physically failing.

If CHKDSK says it cannot open the volume for direct access, close any File Explorer windows or programs using the drive, safely eject it, reconnect it, and try again. Security software or a failing connection can also keep the volume busy.

Do not interrupt CHKDSK once a repair is underway unless the drive has clearly disconnected or stopped responding.

4. Check whether the files were only hidden

Sometimes the files are still present but have hidden, system, or read-only attributes. This can happen after malware or an accidental attribute change.

To remove those attributes from files and folders on the USB drive, run:

attrib -h -r -s /s /d G:\*.*

The switches mean:

• -h removes the hidden attribute
• -r removes the read-only attribute
• -s removes the system attribute
• /s includes files in subfolders
• /d includes directories

Open the drive again in File Explorer after the command finishes. This does not recover deleted data. It only makes existing items visible and writable again.

If hidden files reappear after being removed, scan the computer and USB drive with Windows Security before opening them.

5. Look for FOUND.000 and .CHK files

When CHKDSK finds lost allocation chains on a FAT-family file system, Windows may save them in a folder named FOUND.000. Later repairs may create FOUND.001, FOUND.002, and so on.

Inside, you may find files such as:

FILE0000.CHK
FILE0001.CHK
FILE0002.CHK

A .CHK file can contain a complete recovered file, part of one, or unrelated fragments joined together. Copy the .CHK files to a healthy drive before experimenting with them.

Renaming one to .jpg, .docx, or .mp4 only works when the contents really match that format. Start with files whose type you can reasonably identify by size or content. Keep the original .CHK copy until you have confirmed that the renamed file opens correctly.

For example:

FILE0001.CHK → photo1.jpg
FILE0002.CHK → report1.docx
FILE0003.CHK → video1.mp4

Two older tools designed to identify .CHK contents are UnCHK and CHK-Mate. Keep an untouched copy of every .CHK file before using either tool.

6. Use recovery software when the file system is not enough

If the files are deleted, the directory structure is badly damaged, or the .CHK fragments are not useful, move to a recovery tool.

Install or extract the recovery software on the computer, not on the damaged USB drive. Save recovered files to the computer or another healthy disk. Never write the results back to the source drive during recovery.

PhotoRec may recover old malware along with legitimate files, so scan recovered files before opening them. Its official recovery guide also notes that it usually cannot preserve the original filenames or folder structure.

7. Format only after recovery is complete

Once the important files exist in at least one other location, you can test whether the USB drive is still worth using.

In File Explorer, right-click the USB drive and choose Format. For broad compatibility, use FAT32 when no single file exceeds 4 GB. Use exFAT when you need larger files or regularly move data between modern Windows and macOS systems.

A quick format is fine for preparing a drive that appears healthy. It is not a repair for failing flash memory. If corruption returns, Windows reports bad sectors, or the drive disconnects again, replace it.

Safety and prevention

• Do not install recovery software on the damaged USB drive.
• Save recovered files to your computer or another healthy disk.
• Use Eject or Safely Remove Hardware before unplugging the drive.
• Replace a drive that reports bad sectors more than once, disconnects during use, or corrupts new files.
• Scan the USB drive and recovered files with Windows Security or Malwarebytes before opening unfamiliar files.
• Keep important files in at least two places. A USB drive should not hold the only copy.

Routine formatting does not prevent flash-memory failure. Format the drive when you need to change its file system, erase it for reuse, or test it after recovery.

The short version

For a healthy-looking drive with files already copied somewhere safe, the two commands most often used are:

chkdsk G: /f
attrib -h -r -s /s /d G:\*.*

The order matters more than the commands. Stop writing to the drive, preserve what is readable, check before repairing, recover files to a different disk, and only format after the data is safe.

Symbol guide

Quick reminder

If you find .CHK files in a FOUND.000 folder, copy them to a healthy drive first. Rename and test the copies. Keep the original fragments until you finish recovery.

Recovery status checklist

Created for field techs, makerspaces, and repair benches.