Have you tried taking it to a PC repair shop? Lots of them will run free diagnostics to figure out what’s wrong with it. There’s a lot of things it could be other than the hard drive going bad. And even if it is, as awful as it’d be if you didn’t have backups for the content on it, that’d be one of the cheapest parts to replace. Hope you can figure something out and get some good news soon.

Yeah, as Jaki-kun, mentioned above. I'd have it checked out to see what the root problem is. Could be that the problem isn't the storage drive.

This sounds like it may be one of your RAM and not the storage drive. Which if it is the issue, also usually a relatively cheep piece to fix (Probably similar cost to a drive) unless it's integrated.