Instructions
Locate the front "Power" button on the front of the PS3. If you have the original PS3, these are touch-sensitive buttons. If you have a PS3 Slim, these are physical buttons.
Hold down the "Power" button for five seconds until your monitor goes blank. This is called a hard reset.
Wait 10 seconds and push the "Power" button again, without holding it down. This will power the PS3 back up.
Press the "PS" button on your PS3 controller to turn it on and the controller will connect to the PS3.