do not reformat yet.
is it possible to boot in safe mode? try that, I had a problem similar to that before
cant enter the windows, but when I chose the safe mode it did
you can copy your files if youve entered the windows
try to buy a new hard disk, then use it as the primary, and see if your old hard disk will function as a slave.
sounds a bit expensive but it might work, if it works, you can copy your files then