Don't Panic! Your Files Are Probably OK
Try these steps if your computer will not turn on and is showing no sign at all of receiving power — no fans running and no lights on the laptop or tablet, nor on the front of the computer's case if you're using a desktop.

Important: You may or may not see a light on the back of your desktop PC depending on the kind of power supply you have and the exact cause of the problem. This goes for the power adapter you might be using for your tablet or laptop as well.

Note: Don't worry about the monitor yet, assuming you're using a desktop or an external display. If the computer is not turning on because of a power issue, the monitor certainly can't display anything from the computer. Your monitor light will likely be amber/yellow if your computer has stopped sending information to it.