Computer won't power on?

Just tried to turn on my main desktop computer there and it won't start. I push the start button and get nothing. No sound or any hint of anything. I have checked all the plugs and they are all working fine. I have checked the power cable to see if it works ok. I plugged it into my printer and it work fine. Everythiing is still plugged into the PSU and its switched on. Switched off for a bit there and back on again, nothing. The computer was working fine last night. Now nothing at all happens when i press the power button. Any ideas?

 

Trace the wire from the power button to the motherboard. It should terminate in a small connector towards the bottom of the motherboard. Remove the connector and short the pins with a small screwdriver for about a second. This acts as a temporary power button to rule out that your power button is broken. There is very little risk involved, just be careful not to scratch the motherboard.