Reboot
Seems like the computer is already off and pushing the power button is ineffective...it must be an issue with power.
Alternate
Does the PC also have a voltage setting, and if does, did it get changed to an incorrect setting?
Unplug all external devices, such as printers and scanners, except the monitor. If the computer powers on without the devices, add the external devices back one at a time until you can identify the problem device.
Electricity
Is the PC's power cable plugged firmly into a wall socket or power strip, and is the power strip on? If so, try plugging the PC or the power strip into another wall socket. Also, check that the power cable is firmly connected to the PC's power-supply outlet.
Cables
Double check the PC's power cable is plugged firmly into a wall socket or power strip. If it is connected to a power strip, make sure it is "on".
Check that the power cable is firmly connected to the PC's power-supply outlet.
Ms. Powers is faced with a black screen on her computer. Pushing the power button doesn't bring any life either.
With 20 faces staring at her and waiting for her next move, what can she do?
------------
Click on the letter below that you think is correct.
(C-cables, L-lights, E-electric, A-alternate, R-reboot)
Or
Scroll through all options.
Wake Up!
Lights
Are there any lights?
If no, checking cables and electricity is the way to go.