You've probably read the article "9 signs your computer's hard drive is about to die" and if you haven't, you should. Hard drives telegraph their demise, sometimes well in advance. Usually you don't realize it until after the fact.
So it was with my experience, when a 2TB Seagate drive died on me out of nowhere. Turned out the drive had been sending signals, I was just missing them. As comprehensive as Bill Snyder's list was, there's a few more to add from my experience.
The fact that hard drives give off warnings ahead of its demise is good, and probably the one plus over an SSD. Multiple people have reported that SSDs give no warning. One day you go to power up your PC and nothing. It's dead.
So here's a few more signs your hard drive is about to grind to a halt, as experienced by me:
1) It stops showing up in the BIOS/UEFI. In the weeks prior to its demise, my Seagate wouldn't show up in the storage devices in my PC UEFI menu. I'd see the C: boot SSD, the backup drive and the DVD-RW but not D:, a.k.a. Data. But it was there when I booted so I paid it no mind.
2) The drive disappears from the Windows File Explorer. There were times I'd open Explorer and the D: drive wasn't there. Other times, the E: drive disappeared. Turns out the E: was being fouled up because the two drives were daisy chained on the same power cable.
3) Extreme delays with apps that don't touch the drive. I had this problem with a few apps that, even though they ran on the C: drive, still polled all of the drives in my system. When they got to the dying drive, they stalled.
4) Copying a file to that drive damages the file. That's how I lost my Outlook contacts. I thought there was a problem with the C: and tossed the .PST file over to the D: drive. Turns out the D: was the bad one.
5) Blue-screens during disk activity. A blue-screen is supposed to stop a hardware problem in its tracks before it gets worse. When it happens during basic drive activity – in my case, Word autosaving my work – then there is likely an issue with the drive.
If you suspect a dying drive, there is a nice utility from Western Digital that works on all drives called Data LifeGuard Diagnostics. It will perform a quick or in-depth check of your drive. Another is HDDScan, which also does a check of your drives, but does not work on Windows 10.
Between my list and Bill's article, that's a lot of signs, but they have one thing in common: an extreme slowdown in the hard drive and/or PC. An extreme slowdown is almost always drive-related. Bad RAM means you crash. Ditto a CPU problem, although a dead heat sink might slow a PC way down.
Hard drives die, that's inevitable, although their durability is greatly improved. I remember when you could screw up the drive heads just by bumping the desk too hard. If you know what to watch for, you can catch a dying drive well in advance of its last spin.