My computer doesn't shut down or sleep, not even on safe mode

Hello all, Recently, two days ago, I tried to turn on my computer, and heard a weird alarm on startup, so I did a hard shut down (pressed the shut down button too long), and turned it on again. since then, the computer was never able to shut down or sleep, it freezez at the black screen right before it should turn off everything. I tried formating and re-installing windows 7 Ultimate X86,...