I have screen, desktop problem.

I was working on Ubuntu 12.04 32-bit and everything was fine until I lost electricity.
Now when I'm turning on computer I don't get any messages on my screen - it's only 'not connected'. I tried other monitor, other cable. I removed power supply cable and I put it again but it's still the same - I don't even see message how to enter bios/terminal..

What could happened and what I can do now? I tried to press F2, ctr+alt+F1, ctr+alt+F2, ctr+alt+F3 but still I don't get any output.

Any solutions?