From what you say it does seem likely that you have hard drive problems, but not certainly.
However, as a first step you need to do what you can to recover any data you have on the hard drive that isn't already backed up. There are at least two reliable ways of doing this. One is to remove the the HDD and slave it to another computer using a USB caddy or something similar. If the drive runs at all you will be able to move the data either to this other computer or to external strorage.
The other way is to use a lightweight self-booting Linux distro like Puppy which runs entirely in RAM and doesn't use your hard drive at all to see first if the computer will run and then to move your data, if it is accessible, to external storage. You can get Puppy - a free download - from here, along with instructions on how to use it :
Assuming you have access to another computer all Puppy will cost you is a little time and a blank CD and is the way I would go in this situation since it will test the CD drive, the mobo, the RAM and the display - not as in 'testing' but if it gets to the Puppy desktop you will know these areas are working.
A couple of points from your post that need clarifying : you say "you tried a bootable Windows disc, nothing" as an example. Does this mean the drive didn't spin, the disc itself didn't work or the computer just didn't boot ?
Edited by Chris Cosgrove, 20 February 2016 - 05:19 PM.
This is to test the 'edit' function