When you turn it on, do you hear the typical power-on beep and hard disks powering up?
If there is absolutely zero sound and response, it could likely mean that your power supply has kaput.
If there are some sounds, then nothing showing on screen, then could be motherboard or ram problem.
In any case, better ask a friend who's familiar with CPUs or bring to your nearest PC shop for help.
p/s: How did you post this help request if your PC can't power on, using cyber-telepathy?