Instructions
Check all of the cables which plug into the PS3 and your television and secure any loose connections. Pay particular attention to the HDMI cable which allows your system to play games in HD (high definition) -- often, it looks tight, but you may still need to maneuver it in place firmly.
Change the video output settings if necessary. If your PS3 is set up for standard A/V cords to connect to the TV set when you are actually using a HDMI cable then you will get no picture. It's the same problem vice-versa. Ensure the output settings mirror the cables you are using.
Reset the resolution setting. Have you been using your PS3 on an HD television and are now going back to a standard definition unit? If so, your machine may still be configured for HD and that is why you are not getting a picture. Go into your settings and switch back to standard resolution and restart your system.