USB Drive Not Recognised — What to Try First
Short answer
Open Disk Management on Windows before anything else — a drive that is missing from File Explorer but visible there is intact and simply needs a drive letter assigned, which takes seconds. Never accept an offer to format a drive containing files you need; formatting erases it. Work through port, cable and Disk Management first, and only format a drive you are willing to lose.
On this page
The drive goes in and nothing appears. No sound, no new letter in File Explorer, or a letter that opens to an error. Before trying anything, understand the one rule that matters here:
Do not format the drive. Windows will offer to, often insistently, and accepting that offer destroys the file system index and makes recovery far harder. A drive that Windows cannot read is frequently a drive whose files are entirely intact behind a problem that has nothing to do with the data.
Work through the causes in order of likelihood and reversibility. Nothing in the first four sections risks anything.
Triage
| What you see | Likely cause | Where to go |
|---|---|---|
| Nothing at all, no sound | Port, cable or power | Physical checks |
| Appears in Disk Management, not Explorer | No drive letter assigned | Assign a letter |
| Shows as Unallocated or RAW | Partition or file system damage | Recovery, not formatting |
| Letter appears, opening gives an error | File system corruption | chkdsk, then recovery |
| Yellow triangle in Device Manager | Driver problem | Reinstall the device |
| Works elsewhere, not on this PC | Letter conflict or driver | Assign a letter |
The second row is the single most common cause of a drive that seems invisible, and it is fixed in about fifteen seconds.
1. The physical checks
Fast, and they rule out a surprising proportion.
- Try a different port. On a desktop, use a rear port — those are wired directly to the motherboard and are more reliable than front panel ones.
- Remove any hub, dock or extension cable. Plug directly into the computer. Bus-powered drives frequently work directly and fail through a hub that cannot supply enough current.
- Try a different cable, for anything with a separate cable. A charge-only or worn cable produces exactly this symptom, and the same logic is covered in Android phone not showing up on PC over USB.
- Try another computer. This splits the problem cleanly: a drive that works elsewhere has a healthy file system and the problem is on this PC. A drive that fails everywhere is more likely hardware.
- Listen and feel. A portable hard drive should spin up with a faint whirr. Silence, or repeated clicking, points at mechanical failure — and a clicking drive should be unplugged immediately and taken to a data recovery service if the contents matter.
- Check the light, if it has one. No light at all usually means no power reaching it.
2. Disk Management — the important one
File Explorer only shows drives that have been assigned a letter. Disk Management shows everything the computer can see at all.
Press Win+X and choose Disk Management, or press Win+R and run
diskmgmt.msc.
Find your drive in the lower pane, identified by its size. What you see tells you the cause:
It has a size and a file system, but no letter. Right-click the partition → Change Drive Letter and Paths → Add → pick an unused letter → OK. It appears in File Explorer immediately. This is the fix in a large share of cases, and it happens because the letter the drive wants is already taken by a mapped network drive or another removable device.
It says Unallocated or RAW. The partition table or file system is damaged. Do not create a new volume and do not format. Both of those destroy the recovery path. Go to the recovery section below.
It says Healthy with a letter, but Explorer gives an error. File system
corruption. Try chkdsk below.
The drive does not appear at all. Back to the physical checks, then Device Manager.
3. Device Manager
If Disk Management does not list the drive, check whether Windows sees the device at all.
- Press Win+X → Device Manager.
- Expand Disk drives and Universal Serial Bus controllers.
- Plug the drive in and watch the list refresh.
- A yellow warning triangle means a driver problem. Right-click → Uninstall device, unplug the drive, then replug it so Windows reinstalls the driver cleanly.
- An “Unknown USB Device” entry usually means the drive’s controller is failing or the connection is marginal. Try another port and cable first.
- Nothing changes when you plug in means no connection is being made at all. That is physical.
Also try View → Show hidden devices, then remove any greyed-out storage entries. Accumulated phantom devices can block a new one from enumerating.
4. chkdsk, for a drive that opens with errors
Only run this when the drive has a letter and Windows can see a file system on it. Running it against a RAW drive does nothing useful.
Open Terminal or Command Prompt as administrator and run:
chkdsk E: /fReplace E: with your drive’s letter. It checks and repairs file system
structures. Expect a few minutes on a USB stick and considerably longer on a
large external hard drive.
A caveat worth knowing: chkdsk occasionally moves orphaned data into a
found.000 folder as numbered .chk files, losing the names. That is better
than nothing but it is not clean recovery. If the files are irreplaceable, run
recovery software before chkdsk rather than after.
5. If the drive shows as RAW or unallocated
This is where the formatting warning matters most. Windows will prompt you to format a RAW drive every time you click it, and the prompt looks like the obvious next step.
Formatting erases the drive. Everything on it goes, and no recovery tool reliably gets it back afterwards. The files are, at this moment, still physically present — the index describing where they are is what is broken.
The order that preserves your chances:
- Stop writing to the drive. Any write can overwrite the data you want.
- Run recovery software against it as-is. Recuva and PhotoRec are both free and both read the raw drive and reconstruct files from their contents rather than from the index. TestDisk can sometimes rebuild the partition table outright, which restores everything at once.
- Recover to a different drive. Writing recovered files onto the drive you are recovering from overwrites the very data still being read.
- Only then consider formatting, once you have what you need or have accepted the loss.
Expect imperfect results. Recovery frequently returns files with generic names and no folder structure, and some files come back damaged. For photos and documents it works well; for databases and large archives, less so.
6. Mac-formatted and Linux-formatted drives
A drive formatted on a Mac with APFS or HFS+ will show in Disk Management with a partition Windows cannot read, and Windows will offer to format it. It is not damaged. Windows simply does not read those file systems without extra software.
The same applies to ext4 from Linux.
Options: read it on the machine that made it and copy the files off, install a third-party driver that reads the format, or reformat to exFAT — which erases it, so only after the files are safe.
If you need a drive that works on Windows and macOS both, exFAT is the format to use. FAT32 also works everywhere but cannot hold a file larger than 4GB, which catches people out with video.
What to expect
The drive letter fix in Disk Management resolves a large share of cases instantly, and the physical checks resolve most of the rest. Between them, most people never need the recovery section.
A drive showing as RAW is recoverable more often than it looks, provided nobody formats it in the first five minutes. That is the whole reason this guide is ordered the way it is.
What is not recoverable at home is mechanical failure — a hard drive that clicks or does not spin has a physical fault, and software cannot reach the data. Professional recovery services can, at a cost that is usually in the hundreds rather than the tens. Whether that is worth it depends entirely on what is on the drive, and the answer is rather often that a drive you were using as the only copy of something important should have had a second copy. That is a hard thing to hear at this point, and it is still the thing that would have helped.