You plug in a USB stick or external drive and nothing happens, or Windows says "USB device not recognized." Most of the time the cause is a port, a missing drive letter, a power-saving setting or a confused driver. Check them in this order.
1. Try another port and cable
- Plug into a different USB port. On desktops, the rear ports (wired straight to the motherboard) are more reliable than front-panel ones.
- Remove any USB hub or extension cable and plug directly into the PC.
- External hard drives often fail because of a bad cable. Try another one.
- Test the device on another computer. If it fails there too, the device itself is probably the problem.
2. See whether Disk Management finds it
File Explorer may hide a drive that Windows has actually detected.
- Right-click Start and open Disk Management.
- In the lower panel, look for a disk matching your drive's size (often labelled "Removable" or Disk 1, Disk 2).
- Use this table to decide what to do next:
| What you see | What to do |
|---|---|
| A volume with no drive letter | Assign a letter (step 4) |
| Unallocated | It needs a new volume; recover any data first |
| RAW, or a prompt to format | Recover data before formatting |
| Nothing at all | Continue with steps 5 to 7 |
3. Don't format in a panic
If Windows says "You need to format the disk before you can use it," don't click Format yet. Formatting erases what's on the drive. If the files matter, read our file recovery guide first.
4. Assign a drive letter
- In Disk Management, right-click the USB volume and choose Change Drive Letter and Paths.
- Select Add (or Change if a letter exists) and pick a letter no other drive is using.
- Select OK. The drive should appear in File Explorer.
5. Stop Windows from powering down USB ports
Windows sometimes cuts power to USB controllers to save energy, and devices then vanish.
- Open Device Manager and expand Universal Serial Bus controllers.
- Double-click USB Root Hub (repeat for each one).
- On the Power Management tab, untick Allow the computer to turn off this device to save power.
You can also open Control Panel > Power Options > Change plan settings > Change advanced power settings > USB settings and set USB selective suspend setting to Disabled.
6. Reinstall the driver
- In Device Manager, look under Disk drives or Universal Serial Bus controllers for an entry with a yellow warning icon, often called "Unknown USB Device."
- Right-click it and choose Uninstall device.
- Unplug the drive, restart the PC, and plug it back in. Windows installs the driver fresh.
7. Update Windows and chipset drivers
Install everything in Settings > Windows Update, and check Advanced options > Optional updates for driver updates. The chipset or USB drivers from your motherboard or laptop maker's support page can also help, especially on older PCs.
FAQ
Windows plays the "connected" sound but the drive doesn't show up.
That means the device was detected. Check Disk Management in step 2; a missing drive letter is the usual reason.
My external hard drive is clicking.
Clicking often means a mechanical fault. Keeping it powered can make things worse, so if the data is important, contact a professional recovery service.
Only one port is dead.
That port may be damaged or dusty. Gently clear any debris; if it still fails, use another port.
The drive works on Mac but not on Windows.
It may be formatted with a Mac-only file system such as APFS. Windows can't read it without extra software. Copy the files off on the Mac before reformatting it as exFAT.