A five-pound lead or a seized motor produces the same blank window as just about anything else, which is why guessing can be very costly here. As you work your way through each of these hurdles in order, you will get some idea of what you have within a matter of minutes, without needlessly burning up any of the drive's remaining life to find out.
Between the physical socket and an icon on your desktop, a USB drive must get through three things in sequence. First, it needs enough electrical power to "spin up" or "wake up". Second, the computer needs to detect that a storage device exists on the bus at all. Third, the volume on the device must be readable enough to be recognised by the system, mounted and given a name. Nothing shows up until all three have been passed, which explains why the symptom will appear the same regardless of how different the cause may be.
Each hurdle will leave its own type of evidence. Power will show itself through an LED, a very soft whirr, or a slight resistance you can feel through the shell if you rest your fingertip on it. Recognition will appear in Device Manager on Windows or in System Information under USB on a Mac; both of these can list a drive as a device even when the volume never mounts. Mounting is the part you are normally going to see, and it is the last to happen. A warm, spinning drive with no listing in Device Manager has failed at hurdle two, which points at the bridge electronics or the firmware on the disk itself rather than at a cable. A drive that is listed as a device but does not have any usable volume has failed at hurdle three, and most of the time a failure of this nature is a filing problem rather than a hardware one. Sorting the fault into one of those three buckets is most of the job.
Before you even consider whether any of this matters, try listening to the drive for about ten seconds while the room is completely quiet. Regular ticking every second or two, a short rasp followed by a period of silence and then the same pattern again, an unending spin-up that never settles, or a series of electronic beeps from the case: any of these means the mechanics are involved. The ticking is the head assembly sweeping back and forth and being reset, because it cannot find its bearings. The beeping is a motor drawing current it can't convert into rotation, typically because the spindle has seized up or the heads are sitting on the platter surface and holding it in place.
This overrides all other items on this page. Heads which are not reading properly are still flying a fraction of a micron over the surface of the platters; once one has touched, it will take material with it and spread the debris throughout the inside of your drive. The damage builds up with each second your drive remains switched on, and it does not repair itself. There is no combination of software, freezer myths or firm taps that can reverse it. Switch it off at the wall, leave it off, and go straight to the final section. Everything in between is written for a drive that is silent.
Assume the least interesting explanation until it has been ruled out, because the least interesting explanation is right more often than the impressive ones. Start with the lead. The majority of bundled USB-C cables are built down to a price, and many of the spare leads found in household drawers are wired for charging with their data pairs missing entirely, leaving a drive that lights up but is never seen by your computer. Borrow a lead you know carries data, instead of hopefully inspecting the old one.
Then the port, where the problem is usually current rather than data. A 2.5-inch bus-powered drive can draw more during spin-up than a front-panel header, an unpowered hub or a monitor's built-in socket will provide, and a drive that browns out mid-spin-up will drop off the bus, come back on again, and leave you stuck in a loop. Connect it straight into a port on the back of a desktop or directly into a laptop, and if a Y-cable was provided with your drive, use both ends of it. After that, connect it to a different computer entirely; this single step separates a fault in the drive from a fault in a driver, a chipset or a USB controller, and it takes less than a minute.
Desktop units that plug in at the mains deserve their own paragraph: a Seagate Backup Plus Hub, a WD Elements Desktop, a Buffalo DriveStation, a G-Technology G-Drive, and anything else with a barrel connector on the back. Where there is zero light, motion or noise, the small external power brick has failed many times more often than the drive inside it. They are the single most common non-fault described to us down this freephone. Before borrowing a power supply from something else, make sure you match all three things printed on the label (voltage, current rating and the polarity symbol), as putting 19 V into a 12 V unit will turn a ten-pound problem into a board-level repair.
Inside the shell there are two separate devices, not one. The disk speaks either SATA or NVMe, while the outside world speaks USB, and there is a very small bridge board between them that translates between the two and has its own power section, its own firmware and failure modes all of its own. So when this board fails, you typically see the classic hurdle two behaviour: the disk receives power, you can feel it spinning, and yet no matter how many computers you connect it to, none of them will admit that anything is attached. On the bench the disk is simply connected directly, leaving the bridge out of the circuit, and that is why a unit that appears completely dead on a kitchen table is often an unremarkable job.
This is not an argument for cracking the case open yourself, and there is a specific reason. On many of today's portables (most WD My Passport units, several SanDisk and Samsung portable SSDs, various rugged ranges), the encryption is performed by the bridge, not by the operating system, whether or not you've ever set a password. Remove the bare disk from that housing and it will read as random noise on any computer anywhere in the world, because the key material was on the circuit board you have just discarded. Get a quote first, then send the whole unit, complete and intact, in its enclosure along with its cable and power supply, to someone who has the equipment to work with it and keep the pairing.
One of your habits is worth breaking while you are here. If the drive shows up on the third attempt this week and the eighth attempt next week, then the drive isn't just being finicky, it's failing gradually and giving you a warning. Every mount you spend trying to prove it still works is one you can't spend copying files off it. Use those attempts on the folders that matter, your largest and most important files first, and stop as soon as the drive drops out.
Both the Finder (on Macs) and Explorer (on Windows) show a tidied representation of reality in which things that have gone wrong are simply absent. The unedited view of your drives on Windows is Disk Management, which you can reach from the menu that appears when you right-click the Start button. If a disk shows up there with a healthy partition and no letter next to it, it has usually just lost its drive letter as a result of a clash, and all you need to do is assign it a new one, which is safe and instant. There is, however, a description you should watch out for. It will say RAW, or unallocated, or a pop-up will ask if you want to initialise the disk. All three of these mean the same thing: the structures recording where each file starts and stops are damaged. They do not mean your disk is empty.
Do not accept the offer to initialise, and do not accept the separate offer that Explorer will make to format it. Both of these write fresh structures directly on top of the damaged ones an engineer would otherwise use to rebuild your folder tree, and Windows will continue to ask every time you plug the drive in without ever taking no for a final answer. Be just as cautious about running chkdsk on any drive that holds anything irreplaceable: its purpose is to make a volume consistent, not complete, and it will have no problem discarding what it cannot reconcile.
The Mac equivalent is Disk Utility, where you can turn on "Show All Devices" from the View menu to see the physical device above the volumes sitting on it. When a volume appears greyed out below a device that is otherwise present, this is common and frequently recovers in full. As for Erase, it does exactly what it says. First Aid is a repair tool, and running a repair tool on hardware that has recently started making a new noise is the worst possible way to spend the time it has left. Before you conclude anything, rule out the dullest reason of all: NTFS volumes do not natively mount on macOS, and APFS or HFS+ volumes cannot be read by Windows unless additional software is installed. Plenty of drives declared dead are only plugged into the wrong operating system.
Four indicators define this boundary, and any one of them is enough. A new noise from your drive that it was not making a month ago, especially after some kind of knock or fall. A volume reported as RAW that holds anything you'd be sorry to lose. Detection that is getting worse week by week. Or recovery software that ran overnight and produced a whole folder of files which cannot be opened. Beyond that point, carrying on is not a neutral act; it simply consumes the working life required for a proper recovery.
You'll have to put up with some tedium here, as what follows is deliberately dull. Begin by getting a quotation over the telephone or using our free online diagnostic. Then send the entire unit, in its enclosure, with its cable and power supply, and do not remove the disk, as on many of these models the encryption is held on the bridge board. Package the unit so that absolutely nothing can shift around inside the box, and post it tracked and fully insured to Guildford Data Recovery, Building 2, Ground Floor, Guildford Business Park, Guildford, GU2 8XH. That is approximately eighteen miles from Bracknell, roughly forty minutes down the A322 followed by the A3, and if you would prefer to hand it in at the lab yourself, you can drop it off Monday to Friday, 9am to 5:30pm, with no appointment needed. No one will collect your unit (we do not have a van and there is no Bracknell counter), so sending it through the post is genuinely the quickest option available. Two working days after it is booked in, you receive written confirmation of which of the three hurdles it was failing, what can realistically be recovered, and the price: £300 + VAT covers a single hard drive or SSD, with NVMe units charged at the same rate. If you decline the quote, you are only out the cost of return postage, nothing else. The freephone number for any questions you want to ask first is 0800 689 0668, Monday to Friday, 9am to 5:30pm.
A drive that requires three attempts to appear today will require thirty next week. Intermittent detection is not some quirk you should attempt to work around; it is a timer counting down with a fixed amount left on it. Use whatever mounts remain to copy files off the drive, and do not waste them attempting to prove to yourself that it still functions.
Free diagnostic completed within 2 working days of booking in your device, then one fixed written quote, and in most cases you only pay if we recover your data. Cards and USB sticks £250 + VAT, and any single drive or SSD £300 + VAT.