“Corrupted and unreadable”: what Windows is really saying.

NTFS keeps its books in the Master File Table — a giant index recording where every file lives, what it’s called and who owns it. This error fires when Windows reads a page of that index, or a folder’s own records, and gets back something that fails its checks. Your documents and photos are usually still sitting exactly where they were; it’s the directions to them that have been damaged.

Two very different things damage those directions. The benign version: an interrupted write — a USB drive yanked mid-save, a power cut, a crash — leaves half-updated bookkeeping. The sinister version: the sectors physically holding the index are starting to fail, and the corruption is a hardware symptom wearing a software costume. From the error message alone, you cannot tell which you have. That single fact should govern everything you do next.

Every forum answer says the same thing: run chkdsk /f. Here’s what those answers omit. Chkdsk doesn’t recover anything — it makes the file system consistent, and its licence for doing so includes amputating whatever it can’t reconcile. On the benign, interrupted-write version of this error, that’s often fine: minor books get balanced, files reappear, everyone’s happy. That’s the coin landing heads.

Tails is the hardware version. Chkdsk on a drive with failing sectors forces hours of intensive reading and writing across a disk that’s dying — hammering the weak areas, converting wobbly-but-recoverable data into permanently orphaned fragments in a folder called found.000. We meet the aftermath weekly: a drive that needed a £300 careful image now needing miracles. If the drive is slow, hot, noisy, or the error arrived alongside other strangeness, the coin is loaded against you — don’t flip it.

First, triage the drive itself, not the error: is it making any sound it didn’t used to? Is everything on it suddenly slow? Did the error arrive after a knock or a power cut? Any yes puts you on the hardware branch — power down and stop, because the corruption is a symptom, not the disease.

If the drive seems otherwise healthy and the damage followed an unplug or crash, the odds favour the logical branch — but the professional move is still copy before repair: image the volume, run any repair against the copy, keep the original untouchable. That’s exactly the order the bench works in, and it’s why our version of this job doesn’t have a tails outcome. One external drive in our files threw precisely this pattern of unreadable directories — the architecture practice’s Elements — and every drawing came home because nothing was ever “fixed” in place.

The maths of this error is unusually clear. If the drive’s contents are replaceable, run chkdsk with our blessing and enjoy the heads outcome if it comes. If they aren’t, the free diagnostic settles which branch you’re on without spending your one safe chance: fixed £300 + VAT in the single-drive band if recovery is needed, no fee on most jobs unless the files come back, drop-off at Tay House or insured post from anywhere in the UK.