PC didn't wake up; now won't start

[xash]

Try some of the suggestions in this thread:

My computer won't start!

@xash

It appears to be a hardware problem, most likely a dead motherboard or CPU.

Try this:

Disconnect and emove HDD.
Disconnect and remove all RAM sticks.
Power on the computer.
If it gives you a series of beeps, then the motherboard is OK and it might be the RAM that’s causing the problem.
If you hear no beeps, then the motherboard/CPU is most probably dead.

If you hear beeps, try booting with one stick, then the other (if you have multiple sticks of RAM)