Your drive is making noises:
switch it off now

A rhythmic click, a dull knock that repeats at regular intervals; a grinding or scraping sound "like a scratched record"; and a drive that spins for a few seconds and goes quiet without fully starting up. Those three are the internal mechanics failing: heads hitting the end stop or the surface, or a motor that can't get into position. It isn't "the fan", or the case beeping, or a single click from the motherboard speaker when the computer starts: those noises come from other parts and don't involve the drive. Nor does the soft, constant hum a healthy mechanical drive makes while working, which is normal and doesn't change over time. The practical difference is that the bad noise is usually new, repetitive and gets worse within hours or days. If you're unsure which is which, switch the computer off and describe the sound over the phone before using it any further.

It depends on exactly where you are. If the drive is already making the strange noise — clicking, grinding or a start-up that cuts out — the answer is no: switching it on "for a bit longer" to get the photos off is exactly the extra start-up that scratches the platter a little more, and it can turn a recoverable case into one that no longer is. If the noise is new and the drive, at the moment you notice it, still mounts normally, your window is minutes, not an afternoon copying folder by folder: copy the essentials to another device straight away and switch it off as soon as you're done, without leaving it on "just in case". The moment the noise appears during that copy, stop right there and switch off. The general rule, if you have any doubt about whether the drive is already mechanically damaged, is not to take the risk: switching it off and calling costs less than losing what's left by scratching the platter one more time.

No, and it's one of the two tricks that make the most cases worse. The popular idea is that the cold contracts the metal parts and frees something stuck inside, but what it actually does is introduce moisture: when you take the drive out of the freezer and switch it on, the condensation that has formed inside comes into contact with the electronics and the platters, adding electrical or surface damage to a drive that was already mechanically compromised. There's no "safe" way to do it, with airtight bags or particular timings: the problem is the temperature change itself and the condensation it produces, not a detail of how the trick is carried out. The other trick doing the rounds, just as harmful, is tapping the drive to "unstick" the heads, which in practice usually finishes off whatever was still partly working. Neither replaces switching it off and bringing it in as it is.

Worse, not better. These programs need the drive switched on and spinning for hours to scan it all for recoverable files, and that continuous running time is exactly what you need to avoid when the fault is mechanical: every minute the drive spins with a head touching the surface is new surface being scratched. On top of that, many of these programs save temporary indexes, or the files they find, onto the same drive they're scanning, which can overwrite data that hadn't yet been touched. The combination of the two — a drive running for many hours straight plus writing to the drive itself — is one of the worst there is for a drive with mechanical symptoms, and it commonly turns a case that started out recoverable into one that isn't. These programs make sense on a healthy drive with a simple deletion, never on a drive that's making noises.

No, and that's an easy way to tell whether the problem is mechanical or something else. An SSD has no spinning platters or heads moving over a surface: it stores data in flash memory, with no moving parts inside, so it physically can't produce a click, a grinding sound or the sound of a motor trying to start. If you hear any of those noises, it must come from a mechanical drive: the computer's own, one in a NAS, or an external 2.5-inch USB drive that has a mechanical disk inside rather than flash memory. When an SSD fails, it does so differently, with no audible warning: it stops being detected, switches to read-only mode, or files start getting corrupted for no apparent reason. So if your computer is making noises and you don't know whether the internal drive is mechanical or an SSD, that noise is already giving you the answer.

Sometimes the fault is only in the circuit board attached to the outside of the drive, and in that case replacing it with a compatible one can fix it without touching anything inside. The trouble is that telling from the outside whether the fault is purely electronic, or whether something is also broken in the heads or the motor, isn't reliable from the sounds you hear: a click can come from the board failing to power the motor, or from a head hitting the platter, and they sound alike to anyone who hasn't seen inside hundreds of times. Swapping the board blind, without knowing the real cause, may fix nothing or may even damage the drive further if that wasn't the problem. And opening the drive at home "to have a look" has a separate cost: the inside can't tolerate the dust in an ordinary room, and a platter with a speck on it can no longer be read properly, which can't be undone afterwards.

Yes. Switching the drive off doesn't erase or change anything stored on the platters: the data stays exactly where it was, in the same state, for as long as the drive is stopped. What can keep erasing or damaging data is switching on a drive whose mechanics are already compromised, because every start-up means the platters spin up again and the heads try once more to position themselves over them, and if a head is already touching the surface, each revolution adds a new scratch over sectors that may previously have been intact. That's why a stopped drive is, quite literally, the only state in which the damage doesn't progress: nothing improves on its own, but nothing gets worse while it stays off. This holds whether the drive has been off for an hour or for several weeks: the time it spends stopped, within reason, doesn't change the diagnosis or the odds it had at the moment it was switched off.

It depends on whether the drive has to be opened or not, which is the difference between a logical and a physical fault, and on how much the drive was handled before it was brought in: switching it on several times after the noise started, or running recovery software on it while it was already failing, usually makes the case more expensive and complicated than almost any other factor. It also depends on whether several drives are involved, as in a RAID or a NAS, and whether the data is encrypted. None of these factors can be assessed over the phone or from a description of the noise, so we don't give fixed prices without seeing the drive first: the diagnosis costs €40 to €60, is deducted if you accept the quote, and the price is given before anything is touched, not afterwards. In the meantime, the only thing you control is not switching it on again, because that's precisely what most affects the prognosis and the final cost of the case.