My computer won't show a Start Up menu at all

My computer suddenly shut down on me tonight. I've had previous battery problems (hp compaq on windows 7) so I thought this could be it, so I started Windows regularly. It then tried "updating" right away, with these .exe's I had never even seen before. So I shut it down immediately. When trying to start Windows repair, it shut down on me also. Then when I read about tapping the f8 button, I turned on my computer to try this and there is nothing. No start up or anything. The power button comes on but the fan doesn't run, the screen doesn't light up. I want to try to save my files, but it seems like this might not be possible Any tips?