1 Power off, unplug, replug all cables to hard drive, verify both ends of data cable to hard drive. See if resolves
2 Power off - let PC cool completely. leave off 1-2 hours. Try again - if it works, get your data off of the drive just in case.
3 - This is only if it's a spinning platter disk drive. Take hard drive out of PC, set it on something like a large book cover or cardboard on floor or counter top so it's not on carpet (static is bad). Spin it like a top with it flat on the table a few times each direction and a good bit of wrist snap. This will sometimes get the mechanical parts inside to move out of a stuck position. Yes, I've had this work for me. If it works, get your data off immediately.
4 - I've done this 2-3 times with success on spinning platter drives. It can work but once you get it running copy all data off immediately and don't plan on it working again afterwards as it's not good for the drive. You are deliberately making it contract then expand as the metal cools and is heated back up which can free up stuck mechanical components. Put in a plastic ziploc bag, then put it in the freezer for a couple of hours. Put it in your pc and fire it up and get the data off immediately.
5 Send it to a data recovery place. It will be expensive. If you're willing to pay someone to recover the data, don't freeze it, do this instead.
If your pc never works for more than a month, you should learn what's going on with it and resolve that.