They never did away with the free upgrade to 10. Still works, just not really advertised. If you have a product key for 8 or 7, you can still use it to activate 10. My 10 Pro license I run was yanked off a recycled Win 7 Pro Dell machine going in the trash.
Also, would be really great if members would fully explain on what they were actually trying to do in their first post instead of it coming out in later posts. Kinda hard to help someone when they don't fully explain their situation.
You need to reinstall Windows. I still advocate 10, you can bypass the product key when prompted and the activation, if 8 was previously activated on that machine, will be automatic. This should walk you thru the whole thing.
You most likely need a new hard drive. The old one has probably failed to the point where nothing will fix it. From the sounds of it, it would be in your best interest to take it in have someone do this for you. If you don't feel like spending money on this old of a system then go buy a new one.
Because the new installation doesn't give a crap about files currently on the disk? I don't feel like you're really trying at all and just resigning to defeat, despite having a relatively simple path to resolution.
It most likely won't activate because you probably had windows 8 or 10 Home installed previously. A Home key won't activate anything other version such as Professional, Ultimate, Enterprise. you need to install the same version of 10 that was installed previously so that it will activate. `