My ps3 powers up, but I get no picture or sound.

Put your PS3 in standby mode (hold the power button until the light turns red) then release, and hold the power button again for about 10 seconds, or until the light beeps a second time. When the PS3 restarts, it should display on whatever it finds plugged in first.

FIRST NOTICE IF UR HDMI CABLE IS WELL CONNECTED BECAUSE IF IT ISNT NOTHING WILL APPEAR ON SCREEN

If your PS3 powers up but you arent getting picture or sound there are a few things you can try to fix this:

1. Check that the HDMI cable is plugged in properly. Borrow another HDMI cable if possible to see if this fixes the problem.
2. Check if your TV is on the right setting or whether it is actually on in the first place.
3. Perform a console settings reset (this will not delete your save games or user data) At the following link I have a free guide to resetting your PS3 safely and correctly to fix your PS3 powering up with no picture or sound.