# How to Fix a Corrupted USB or External Hard Drive

URL: https://www.mytechnician.tech/tips/fix-corrupted-usb-external-drive/
Published: 2026-04-16 | Updated: 2026-08-10 | Author: Ankit Kumar
Tags: Data Recovery, Storage, Fix
Summary: USB drive or external HDD asking you to format it? Stop. Repair a corrupted Windows drive with chkdsk, recover the files, and avoid permanent data loss.
Recommended app: RecoverPro — https://www.mytechnician.tech/apps/data-recovery-pro/ (Microsoft Store: https://apps.microsoft.com/detail/9MZ613NS5TNN?hl=en-us&cid=mytechnician-web). Optional; every step below uses built-in Windows tools.

## The Problem
You plug in a USB stick or external drive and Windows offers to **format** it, or reports that the file or directory is corrupted. The file system index is damaged; the data underneath is very often still intact.

> **Do not click Format.** Not yet, and not "just to see". Formatting rewrites the file system and makes recovery substantially harder.

## The Order That Matters
This is the part most guides get wrong. If the files matter more than the drive:

**Recover the data first, repair the drive second.**

`chkdsk` writes to the disk. On a healthy volume with minor index damage it fixes things neatly. On a badly damaged or failing drive it can move data into `FOUND.000` folders as numbered `.chk` fragments, or make things worse. If the contents are irreplaceable, image or recover before running any repair tool.

## Why It Happens
* Unplugging without ejecting, while a write was still buffered.
* Power loss during a write.
* A failing USB port, a poor cable, or an underpowered hub.
* The drive itself beginning to fail.

## Step 1: Rule Out the Simple Things
1. Try a **different USB port**, directly on the motherboard at the rear of a desktop.
2. Try a **different cable**—especially with 2.5-inch portable drives, where a marginal cable causes exactly this.
3. Try the drive on **another computer**.
4. For a desktop external drive, confirm its power adapter is connected and working.
5. Listen. Clicking, beeping, or a repetitive spin-up-and-stop means mechanical failure—**stop immediately** and go to the last section.

## Step 2: Check What Windows Sees
Right-click **Start** → **Disk Management**.

| What it shows | Meaning | Next |
|---|---|---|
| Healthy with a drive letter, but Explorer errors | File system damage | Step 3 |
| **RAW** | The file system is unreadable | Step 4 — `chkdsk` will not help |
| **Unallocated** | Partition table lost | Step 4 |
| No drive letter | Simple assignment problem | Right-click → **Change Drive Letter and Paths** → **Add** |
| Not listed at all | Hardware, cable, or power | Step 1, then the last section |

## Step 3: Repair the File System With chkdsk
Only when Disk Management shows a healthy file system, and only when you accept the small risk described above.

Open **Terminal (Admin)** and run a **read-only scan first**:

```cmd
chkdsk X: /scan
```

Replace `X:` with the actual drive letter. This reports problems without changing anything.

If it reports errors and you are ready to repair:

```cmd
chkdsk X: /f /r /x
```

* `/f` fixes file system errors
* `/r` locates bad sectors and recovers readable data
* `/x` dismounts the volume first

On a large drive `/r` can take many hours. Let it finish; interrupting it mid-write is worse than not starting.

Afterwards, check for a `FOUND.000` folder in the root of the drive. Recovered fragments land there as `.chk` files, and some can be renamed back to their original extension.

## Step 4: RAW or Unallocated — Recover, Do Not Repair
When the file system is gone, `chkdsk` reports *"The type of the file system is RAW. CHKDSK is not available for RAW drives."* That is expected, not a further fault.

The data is still physically present. What is missing is the map. Recovery software scans the raw sectors for file signatures and reconstructs what it finds.

1. **Never write anything to the affected drive**, including installing the recovery tool.
2. Install the tool on your system drive, and set the recovery destination to a **third** location with enough free space.
3. Run a quick scan first, then a deep signature scan if needed.
4. Preview files before recovering, and recover everything you care about in one pass.

> **Technician's solution:** when standard tools fail on RAW or accidentally formatted external drives, [RecoverPro](https://www.mytechnician.tech/apps/data-recovery-pro/) carves files from raw sectors and writes them safely to a different drive.

For a general walkthrough: [how to recover deleted files](https://www.mytechnician.tech/tips/how-to-recover-deleted-files-windows/).

## Step 5: Rebuild the Drive Afterwards
Once your data is safe, you can decide whether to keep using the drive.

1. Check its health first: [check SSD or hard drive health](https://www.mytechnician.tech/tips/check-ssd-hard-drive-health-windows-11/). Reallocated or pending sector counts above zero mean retire it.
2. If it is healthy, format it properly: **Disk Management** → right-click → **Format** → **NTFS** for Windows-only use, or **exFAT** for use with Macs, cameras, and TVs.
3. Full method: [partition and format a drive in Windows 11](https://www.mytechnician.tech/tips/partition-format-hard-drive-windows-11/).

## When to Stop and Get Help
Stop using the drive and consider a professional data-recovery service if:

* It clicks, beeps, or grinds.
* It disappears from Disk Management partway through a scan.
* It spins up and immediately down again.
* The data is genuinely irreplaceable and no software has read it.

Repeated power cycles on a mechanically failing drive destroy more data each time. A lab can read platters that software never will—it is expensive, but running recovery software in a loop first often removes that option.

## Prevention
* Use **Safely Remove Hardware** before unplugging, every time.
* Prefer **exFAT** over FAT32 for large drives, and NTFS for Windows-only use.
* Keep a second copy of anything on an external drive—portable drives are the least reliable storage most people own: [set up automatic backups](https://www.mytechnician.tech/tips/set-up-automatic-backups/).

**Getting "The file or directory is corrupted and unreadable"?** That is error `0x80070570` and it has its own diagnosis path: [fix error 0x80070570](https://www.mytechnician.tech/tips/fix-error-0x80070570-file-directory-corrupted-windows-11/).

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Source: https://www.mytechnician.tech/tips/fix-corrupted-usb-external-drive/ — My Technician, free Windows 10/11 troubleshooting guides.
Related tool: RecoverPro (Windows data recovery software to recover deleted files, restore formatted drives, and rescue data from corrupted partitions on Windows 10 and 11.) — https://www.mytechnician.tech/apps/data-recovery-pro/
More guides: https://www.mytechnician.tech/llms.txt