Not showing up · USB device not recognized · not in Disk Management or Disk Utility
An external drive that spins but does not appear can be failing in four quite different places, and the screen barely distinguishes them. The USB bridge may have died, leaving a healthy drive nobody can talk to. The drive's firmware may have failed to load, so the drive spins but never announces itself. The heads may be too weak to read the service area, which usually comes with a click. Or the drive is fine and Windows has simply lost the drive letter, which is the one you can safely check. Whether it says USB device not recognized, shows nothing in Disk Management, or the Mac says nothing at all, the free look tells which of the four it is. One drive is £300 + VAT after the free look, fixed in writing, 3–4 days at the bench, and on most jobs no data means no bill.
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The bridge. Every external drive has a USB board between the drive and the computer. When that board fails the drive spins, the light is on, and the computer sees either nothing or a device it cannot name: USB device not recognized on Windows, silence on a Mac. The drive behind it is fine. On plain enclosures it comes out and is read directly; on native-USB drives such as WD Elements and Seagate's slim portables the board is repaired or carried by a donor; on WD My Passport and My Book the board is the encryption key and is preserved.
The firmware. A hard drive boots from a service area on its own platters. If that area has become unreadable, the drive spins up, the heads settle, and the drive never reports its identity; it may show as a blank device with no size, or under a factory name. The service area is repaired from the terminal on the bench, with every module backed up before a command is sent. Seagate's slim drives lock the terminal, and the lock is undone first.
The heads. If the heads are too weak to read the service area the result looks like a firmware fault and usually comes with a click or a soft tick. That is mechanical, and the drive should not be powered again. The drive letter. And sometimes the drive is entirely well: Windows has assigned no letter, or the partition is one the Mac does not read. Disk Management and Disk Utility will show a healthy drive with its full size, and the only rule is not to click Initialise, Format or Erase while you are there.
| What you see | The usual reason | Where that leaves you |
|---|---|---|
| USB device not recognized / device descriptor request failed | The bridge or the drive's USB board | Board repair or bypass; drive usually fine |
| Nothing in Disk Management, nothing in Device Manager | The bridge, or the drive not starting | Free look |
| In Disk Management with no size, or 0 bytes | Firmware not loaded | Service-area repair from the terminal |
| In Disk Management as Not Initialized | Partition table gone, or a WD drive read outside its box | Do not initialise; send it |
| In Disk Management with a size but no letter | Drive letter not assigned | Assign one; copy off now |
| Spins, ticks softly, never appears | Weak heads | Unplug; head work |
| Mac: nothing in Finder, greyed out in Disk Utility | Volume will not mount | Do not run First Aid twice; send it |
A case number goes on it the day the parcel is opened, and an engineer settles what has actually failed before anything else happens. A drive that clicks or beeps is not powered again; one that spins is read on our own imaging equipment, never in a computer that will retry and time out and retry. Back to you come two things together: a straight note of what is liftable and what is not, plus one figure, fixed and written down. Accept it, or decline and owe us nothing.
Every external drive is two things: the drive, and the USB board that talks to it. The board is checked first, because a failed bridge, a snapped socket or a dead regulator is the whole fault on a good share of jobs, and because on WD's encrypted drives the board holds the key. Where the drive itself has stopped, it comes out of its case onto the bench.
Stuck or failed heads are replaced with a matched set from a donor, seized spindles freed, and firmware faults corrected in the drive's service area from the terminal. The drive is not repaired to be used again; it is made to read once, in a single careful pass, and that pass is planned before it begins.
Nothing is worked on live. The whole drive is imaged once, head by head and weak areas last, with reads timed to what the platters can stand, and the file system is put back together on the image. Encrypted volumes are unlocked there too, with the original board's key or the password you supply, and never on the original.
What was recovered is listed for you first, and only then does a bill exist. Approve the list and it is invoiced; turn it down and it is not — and where nothing has come back, most jobs carry no charge at all. Recovered data travels home on fresh media bought in for your job, with the postage at our end. Your case is not closed until you have opened the files on a machine of your own.
Plugged into three machines, recognised by none, and then unplugged and sent, which was the right sequence. The drive spun perfectly; the USB chip on its own board had failed. A donor board of the same revision was fitted with the original's ROM moved across, the drive imaged through it, and the family's photographs since 2012 came back complete.
Illustrative example — replace with a genuine caseAlmost never. The drive has stopped talking to the computer, which is the bridge, the firmware, the heads or a lost drive letter, and the platters are usually intact. The free look tells which it is and what it costs.
The computer can see a USB device but cannot read its identity, which is nearly always the USB board on the drive or in the enclosure. The drive behind it is usually fine.
No. That writes a new partition table over the one you want back. Close the window and send the form.
Probably not. Assign a drive letter and copy your files off now, then replace the drive. If files fail to copy, stop and send it.
£300 + VAT for one drive after the free look, fixed in writing.
Looking at it is free. Back comes a list of what opened and what did not, together with a single price to finish, set down in writing while you are still free to say no. Until that list reaches you, leave the drive unplugged.