CPU problem. Need help.

I have a problem with my computer. Ithave been running perfectly fine until tonight. when i turn on my cpu, my monitor, mouse, keyboard, or anything that is hooked on it are not working besides the lights and fans in the cpu. im not sure what could be wrong. any ideas?

If you have multiple sticks of RAM, try pulling one out and booting the computer that way. Try this with each stick. If that doesn't apply to you or doesn't work, I might try pulling the battery out of the motherboard and keeping it out for a minute or 2 to clear the CMOS. Then put it back in and try to boot. If that doesn't work, then we might be looking at some serious problems.