My computer is not turning on

First check the computer's power cord to make sure it is completely plugged into the wall socket.
If you are using a power strip, make sure it is completely plugged into the wall socket and that the power switch on the power strip is turned on.
Some power strips also have a built in circuit breaker which usually looks like a black or red button near the power switch. Press the button to reset it and see if that solves the problem.