A USB stick that does nothing when plugged in, an external drive whose light comes on but never appears, or a prompt saying the drive needs to be formatted before you can use it. Almost everyone hits one of these. In most cases the drive itself is fine and the problem is the drive letter, the driver, or power. Work through the steps below from the outside in and the drive usually comes back.

Start by working out which shape the problem takes. Nothing at all, not even in Disk Management. A drive letter that will not open or asks to be formatted. Or no drive letter assigned at all. The three need slightly different handling, but all of them begin with step 1. If the data matters and the drive is asking to be formatted, do not format it. See steps 7 and 8.

Step 1: The physical layer, most common and most overlooked

  • Change the port. Use one on the rear of the case or straight off the motherboard. Front panel ports and USB hubs deliver less power, and a weak front panel is the number one reason an external drive goes unrecognized on a desktop.
  • Change the cable and the computer. Cables on sticks and external drives wear out, so try another one. Plug it into a second machine to see whether the fault is the drive or your computer.
  • Power. If a 2.5 inch drive lights up but will not spin, use a dual-head USB cable or an external power supply. Ports on a monitor or keyboard rarely deliver enough.
  • A USB 3.0 drive in a 2.0 port. Usually fine, but some controllers want a 3.0 port, so try another one.

Step 2: Check whether Disk Management sees it

Press Win + X and open Disk Management, or press Win + R and type diskmgmt.msc. This is where the diagnosis happens.

  • The drive does not appear at all. Windows has not enumerated it, so jump to step 3 for driver and power checks.
  • It appears as a removable disk with no media. Usually an empty card reader slot or a failed controller on the drive.
  • It appears but is unallocated or has no drive letter. Right-click, choose Change Drive Letter and Paths, add, and assign a letter. This is the standard fix for a drive that exists but shows no letter.
  • It appears as not initialized or offline. If there is data on it, do not initialize it, since that wipes it. Try right-clicking and bringing it online. If initializing is truly the only way, confirm your backup first.
  • It shows a RAW file system. The file system is damaged. See steps 7 and 8, and recover the data before formatting.

Step 3: Reinstall the USB driver in Device Manager

  1. Press Win + X, open Device Manager, and expand Universal Serial Bus controllers.
  2. Find the entry with a yellow exclamation mark, either Unknown USB Device (Device Descriptor Request Failed) or your drive, right-click it, and choose Uninstall device. Then use Action > Scan for hardware changes.
  3. If that fails, uninstall USB Root Hub and USB Mass Storage Device one at a time, leaving the delete-driver box unchecked, and reboot so Windows reinstalls them.
  4. Update the chipset and USB drivers. Download the chipset driver for your exact laptop or motherboard model from the vendor, which matches better than whatever Windows Update pushes. If you are unsure of the model, How to Check Your PC's Specs, Model and Serial Number covers msinfo32, dxdiag and the one-line commands.

Step 4: Turn off USB selective suspend

To save power, Windows periodically cuts power to USB ports, which drops external drives.

  1. Control Panel > Power Options > Change plan settings > Change advanced power settings.
  2. Expand USB settings > USB selective suspend setting and set it to Disabled.
  3. Confirm and reboot. Do this on laptops whether on battery or plugged in.

Step 5: Clear write protection

  • Physical switch. SD cards and some external drives have a lock tab on the side, so slide it to unlock.
  • Registry. Press Win + R, type regedit, and go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies. Set WriteProtect to 0, creating the DWORD if it is missing.
  • diskpart. In an administrator command prompt, run diskpart, then list disk, then select disk X, where X is your disk, then attributes disk clear readonly.

Step 6: Repair disk errors

When the drive has a letter but will not open, run chkdsk H: /f /r in an administrator command prompt, replacing H with your letter, to repair file system errors and bad sectors. You can also right-click the drive in This PC, choose Properties > Tools > Check, and follow the prompts.

Step 7: It asks to be formatted, or shows RAW, but there is data on it

When you get the prompt that the drive needs formatting before use, do not format it. Rescue the data first.

  1. Try chkdsk H: /f, which sometimes repairs it into a readable state.
  2. If it still cannot be read, scan with recovery software such as Recuva, DiskDrill, or EaseUS. Save what you recover to a different drive rather than writing it back to the original.
  3. Once you have confirmed the data is backed up, format it, choosing the file system per the next step.

Step 8: Rebuild it, once the data is safe or the drive is empty

Right-click the drive in Disk Management and choose Format. Pick the file system by use case.

  • FAT32. The most compatible, recognized by old TVs, car stereos, and printers, but no single file over 4GB and no partition over 32GB.
  • exFAT. Large files plus cross-platform support on Windows, macOS, and most TVs, making it the default choice for sticks and external drives.
  • NTFS. Windows only, with large file and permission support, which suits an external drive you only use on Windows.

For a small stick that has to carry a single file over 4GB, use exFAT. If compatibility with old devices matters more, use FAT32 and work around the 4GB limit by splitting or compressing.

Symptom lookup

SymptomMost likely causeWhat to try first
Nothing at all, not even in Disk ManagementPower, cable, portStep 1, change port and cable; step 4, disable selective suspend
A chime but no drive letterLetter conflict or unallocatedStep 2, assign a letter in Disk Management
Asks to be formatted, or shows RAWDamaged file systemStep 7, recover data before formatting
Write protected, cannot writePhysical switch or registryStep 5, clear write protection
Light on but not spinning, drops outNot enough powerStep 1, dual-head cable or external power; step 4
Yellow exclamation in Device ManagerUSB driver problemStep 3, uninstall and reinstall; update chipset driver

For a drive that will not show up, change the port and cable first to rule out power and wiring, then look in Disk Management to see whether the problem is a missing letter or RAW. Assign a letter for the first, rescue data before formatting for the second. Driver problems come down to uninstalling and reinstalling in Device Manager plus turning off USB selective suspend. When data is at stake, always recover before you format. Using Safely Remove Hardware instead of yanking the drive cuts the odds of file system damage considerably.