My PC was open and i was doing work when suddenly a beep and then the PC crashed...

When I tried to reboot it, no hard drive found. I entered the setup during restart and even there I can't find a hard drive device.

I tried other hard drive and it worked so my conclusion was:
cables mainboard power supply are all good..

MY harddrive is broken!!!???

Anything I can do to diagnose or to restore or repair or to even to take one last glimpse of the contents just to get some important files then it can totally break?? Anyone here know any restoration?

I'm desperately needed those files.