External hard drive not showing up is the single most common symptom that reaches this bench — and it hides five completely different faults, from a dud cable to dying heads. Here they are in the order we actually see them, each with the one safe response.
Reason one: the link between drive and computer. Cables fray invisibly at the strain relief, USB ports wear loose, hubs under-deliver power. It’s the least dramatic cause and the most common — which is why the only two checks we ever recommend are a known-good cable and a port on the machine itself. If the drive appears, buy a cable and forget this page existed.
Reason two: the enclosure’s own electronics. Desktop externals add a mains adapter to the suspect list (a wrong or failed adapter is a classic silent killer), and every external routes through a USB bridge board that fails far more often than the disk behind it. The tell: no light, no spin-up feel, total silence. Recoverable at component level — but not by shelling the disk out to try bare, because plenty of enclosures encrypt in the bridge and the naked drive reads as noise.
Open Disk Management and a third pattern appears: the drive is listed, but as RAW, unallocated, or with a healthy bar and no drive letter. Windows can see hardware; it can’t read the paperwork. Sometimes that’s trivially benign — a dropped drive letter takes ten seconds to reassign. Mostly it’s file-system damage: a partition table or NTFS structure that’s been corrupted by an unsafe unplug, a power blip mid-write, or the early stages of reason five.
The rule here has no exceptions: decline everything Windows offers. No initialise, no format, no “fix” from an error dialog — each one writes fresh, empty bookkeeping over the damaged-but-present original that recovery reads from. On a Mac the same trap wears Disk Utility’s clothes: First Aid on a struggling disk is hours of forced reading it may not survive.
Reason four: firmware. The drive spins confidently, sounds perfect, and is absent from every screen including Disk Management — because the corruption sits in its internal firmware, the code that lets a disk describe itself. Our case files carry two textbook examples: the Buffalo MiniStation and a practice’s WD Elements. Nothing running on your computer can reach firmware; a bench rig repairs it in the service area and the data is typically untouched underneath.
Reason five: mechanics. Clicking, buzzing, beeping, or a spin-up that never settles — heads, motor or platters in trouble. This is the one branch where every additional power-on does physical harm, so the response is brutal and simple: off at the wall, stays off, comes in as it is.
Sixty seconds of observation sorts almost every case: swap the cable and port (reason one); listen and feel for spin and check the light (two versus four/five); look — only look — in Disk Management (three). Any noise at all, or a drive that’s spinning yet invisible everywhere, means the remaining moves are bench moves.
From there the terms are the same whichever reason yours turns out to be: a free diagnostic names the branch and the odds, externals sit in the fixed £300 + VAT band, and on most jobs nothing is owed unless the files come home — walked into Tay House or posted insured from anywhere in the UK. For the fuller walkthrough of what’s safe to try first, the external-drive recovery guide takes the long road through the same territory.
If a good cable and a direct port haven’t surfaced it, the fault is behind the USB socket — bridge, file system, firmware or mechanics — and all four are routine here. Free diagnosis, £300 + VAT fixed in writing first.