The fan is silent, and there are no LEDs lit.  It seems that the computer is not getting power.  What's next?
When you checked, the computer system is unplugged.  You plug it back in and everything begins working.  Great find!
You checked and the switch is ON.  Someone could have turned off the computer, but not this time.  When you switch from OFF to ON again, nothing happens.  Try another selection.
Your should try some other options before calling.  This might be an easy problem to solve.
