HOW CAN I FIX MY CAR CD PLAYER HAS NO SOUND OR PICTURE?

HELLO I TRIEDS 3 WORKING CD PLAYER'S OUT OF MY OTHERS CAR'S PUT THEM IN MY JETTA ALL WIRES ARE HOOK'D UP GOOD AND TAPED THEY USED TO WORK IN THIS CAR NOW IT WONT SHOW A PICTURE OR SOUND YOU CAN PUT A CD IN AND EJECT IT BUT STILL NO PICTURE OR SOUND ON ANY OF THEY CD DECKS AND ALL DECKS WERE IN MY OTHER CARS AND WORK FINE CAN SOME ONE PLEASE HELP I HAVE NEW FUSES IN THIS CAR ALSO I FRIED ON MY MY DECKS IN THIS CAR BEFORE WHEN HOOKING A SYSTEM UP AND AFTER THAT IT WORK'D FOR A WHILE AND NOW NOTHING PLEASE SOME ONE HELP I DO A LOT OF DRIVING IN THIS CAR AND WITH NO MUSIC IT IS HARD PLEASE HELP AND THANK'S A LOT