Does it give any beeps at all during a post? if you dont get any beeps the problem is likely to be with the ROM, memory or motherboard, if it beeps more than twice you will need to find someone who knows the beep cods for your motherboard.
I have seen a PC fail to start because the reset button was half pushed in. Not being a hardware expert there is not much else i could suggest, replacing the CMOS battery may help but as ypour PC sounds completly dead you may have a BIOS reset to do -unfortunatly I am just guessing here.