In our experience "external hard drive not showing" is the number one complaint we get about external drives (and there's a reason for that), but as far as external hard drive not showing up goes, there are five entirely different faults behind it, from a dud cable to dying heads. Here are the five most frequent causes we see, in the exact order we see them (with one safe way out of each).
First reason: the link between drive and computer. At the cable's strain relief area, cables deteriorate (you can't see it). USB ports loosen up; hubs provide less than required power. Least dramatic of causes yet also the most common, which is why there are only two things you will check in order to determine if your problem exists with either the cable or port on the computer. The first thing would be to try using a new cable. The second would be to test the drive by inserting it into another available port on your PC. If the drive appears, buy a cable and forget this page existed.
Reason two: the electronics in the case. Desktop externals have a mains adapter on the "suspect list" (a wrong or broken adapter is a common silent killer) & all externals go through a USB bridge board that fails much more frequently than the disk it is attached to. The tell-tale signs include: no lights, no spin-up feel, complete silence. Can be recovered at the component level, but not by removing the drive from the enclosure and trying to read it bare, as plenty of cases encrypt in the bridge and the unadorned disk will only read as noise.
In the third pattern, Windows Disk Management shows you the drive. But instead of assigning a drive letter, the drive will show up as RAW, unallocated or have a "Healthy" status. Windows recognises hardware; it does not recognise the data. Some of these are minor issues: a dropped drive letter takes about 10 seconds to correct. Mostly, though, they indicate file system damage. This means either the partition table (the layout for how Windows sees and organises your files) or the NTFS file system itself has been corrupted by an unsafe unplug, a power blip while a write operation was still taking place, or the early stages of reason five.
There are no exceptions to this rule: decline everything Windows offers. Do not let Windows initialise or format anything. Do not use the "Repair" option in an error dialog box. Each time you do one of those things you are essentially writing new, empty metadata over the top of your damaged-but-there file system, which is what data recovery tools attempt to read from. If you're using a Macintosh you'll run into the same pitfall, but the GUI application will be called Disk Utility. Using First Aid on a failing drive can take hours of forced reading that your disk may not survive.
Reason four: firmware. The drive runs fine, looks fine, sounds fine, but doesn't appear anywhere including Disk Management, because the corruption exists inside the firmware. Firmware is software that resides inside a disk drive. It allows the disk to describe itself to the operating system. We've got two great examples of firmware-related failures in our case studies: the Buffalo MiniStation and a practice's WD Elements. None of the applications running on your PC can talk directly to firmware. A bench rig fixes firmware in the service area and usually leaves your files alone.
Mechanics (reason 5). If you have an issue with your hard drive, such as clicking, buzzing, beeping, spinning up but not settling down, or if there are issues with the heads or motor/platter then this could be the area of problem. Each time you turn it on you do further damage to the components of the drive. In order to avoid damaging the drive further the response is simple: off at the wall, keep it off, and it comes in to us as it is.
Sixty seconds of careful inspection can sort out nearly every external hard drive issue: swap cables and ports (reason 1), listen and feel for motion and observe lights (2 vs. 4/5), and go to Disk Management only to see if you can find it there (3). If your drive makes some sort of noise or is spinning but not showing anywhere, then the remaining steps are "bench" moves.
Once you find that branch and compare it to your drive, regardless of which is the case, the next steps remain the same; a free online diagnostic will give you the name of the branch you should go for and the chances of recovering your data, external hard drives fall into a set price (fixed £300 + VAT) and on most jobs we do not charge unless we recover your files. Once you have a quote, you can either walk the drive into our offices at Tay House or send us the external hard drive via insured postage from anywhere in the UK. If you want to see all of the possible options before attempting to recover your data, then take some time reading the external drive recovery guide.
If using a good cable and a straight connection to a port don't produce anything, then there's an issue with what lies beyond the USB socket (bridge, file system, firmware or mechanical), and all four are routine here. We'll provide a free assessment, then we will fix the price at £300 + VAT in writing beforehand.