Put the heat sync back on and see if you can boot the PC. If all works as it should, your CPU is OK. It may have just shut down under hi-temp after the cooler fell off.
the thing is, i cant put it back on because the mounting bracket snapped. I have no idea how this could have even happened.
Also, i have already cleaned my cpu and i have no thermal paste.
but i only turned it on once more after it turned off so wouldnt you think that it should be fine?? it automatically turns off at a certain temp right?