crash

As mentioned before, I have had a number of times the computer would crash, but not the disaster I went thru a few days ago. This is the symptom: No input from keyboard or mouse affects anything and there is no cursor on screen. Usually two lights on the keyboard will flash. I think numlock and capslock, but not sure it's always those. Is there some file I can look at to try and determine what caused the crash, and if I find it, can it be fixed? Thanx for your expertise--doug