Mechanical — the moving parts
Head failure, head crash, seized spindle, stiction. Announced by clicking, grinding, scraping or a buzz with no spin. Needs filtered air and matched donor parts. Deteriorates every minute it runs.
Urgent
Nearly every drive fault falls into one of four classes, and they share nothing except the symptom that brought you here. Two deteriorate every minute the drive runs. Two do not deteriorate at all — and knowing which you have changes what you should do in the next ten minutes.
Mechanical faults deteriorate for as long as the drive has power. Electronic and firmware faults sit still indefinitely. Which one you are holding decides whether the next ten minutes matter at all.
Route, price, urgency and realistic odds all follow from which of these you have — so it is the first thing established.
Nearly every hard drive fault falls into one of four categories, and they are not variations on a theme. A mechanical failure and a logical one share nothing except the symptom that brought you here: you cannot reach your files.
Two of the four get measurably worse while the drive runs. Two do not. That distinction alone is worth knowing before you decide what to do next, because for half of these the most valuable action available is to stop.
With the symptom that identifies each, and whether time is against you.
Head failure, head crash, seized spindle, stiction. Announced by clicking, grinding, scraping or a buzz with no spin. Needs filtered air and matched donor parts. Deteriorates every minute it runs.
A surge, a failed TVS protection diode, aged components. The drive is silent and undetected while the mechanism and platters are untouched. Among the more recoverable faults, and nothing is deteriorating.
Spins normally, sounds healthy, reports zero capacity or a blank model. Service-area modules have become unreadable so the drive cannot describe itself. User data almost always intact behind it.
Deleted files, a lost partition, a formatted volume, corrupt structures. The hardware is fine; the map to your data is damaged. Time matters only because writing overwrites.
You can classify most faults yourself before contacting anybody, and it costs nothing.
If yes, it is mechanical and it is getting worse. Stop here, power it off, and skip the rest of these checks — none of them are worth the runtime.
Put a hand on it. Silence with no vibration usually means the circuit board rather than the mechanism, which is one of the better outcomes.
A drive absent from Windows but present in the BIOS is alive and communicating — that is logical, not hardware. Absent from both points at electronics or firmware.
Zero, a blank model string, or an absurd figure means firmware. The drive is healthy and cannot describe itself.
Detected with unreadable or missing files is logical — a damaged file system or partition table, with the data still physically present.
The practical consequence of the classification, and why the advice differs so sharply.
Mechanical damage compounds. A head flying at the wrong height makes intermittent contact; contact generates particles; particles cause more contact. A drive run for ten minutes after the first noise is a materially different proposition from one restarted every morning for a fortnight, and the difference shows up as regions nothing can read.
Logical damage compounds too, but only if you write. Deleted data survives until something overwrites it — and a running computer writes constantly without being asked: updates, caches, logs, indexing. Stop using the machine and the clock effectively stops with it.
Electronic and firmware faults do not deteriorate. A drive that will not power on is not getting worse in a drawer. There is no clock running, which is worth knowing if you are weighing up the cost — you have time to decide.
In Manchester, a single drive is from £300 +VAT whichever class it turns out to be, fixed in writing after a free 48-hour diagnostic. You are not charged more because the diagnosis sounds worse.
Four: mechanical (moving parts, announced by noise), electronic (a failed circuit board, usually silent), firmware (the drive spins but cannot describe itself), and logical (nothing is broken, the map to your data is damaged).
Listen first. Any noise it did not make before is mechanical — stop there. Otherwise: silent and undetected points at the board, spinning but reporting zero capacity points at firmware, and mounting with missing files is logical.
Mechanical damage compounds every minute the drive runs. Logical damage compounds only if something writes to the drive. Electronic and firmware faults do not deteriorate at all — a dead drive in a drawer is not getting worse.
Usually firmware. Drives load their operating code from a reserved service area on the platters, and if a module becomes unreadable the drive cannot describe itself — so it reports nothing while sounding perfectly healthy. The data is generally untouched.
Usually better. Silence with no spin normally means the circuit board, which leaves the platters and your data untouched. Clicking means the mechanism, and it deteriorates while it runs.
Not the headline figure — a single drive is from £300 plus VAT whichever class it is. What changes is whether a deposit applies: clean-air and donor-part work commits real cost up front, so those jobs take 50% with the balance on success.