problem with my built-in webcam plzz i need help quickly!!!

i have a laptop Dell inspiron 1720 with a built-in webcam.Every time i open the webcam manager and i trie to get photos with the webcam it says that NO SUPPORTED CAMERA DETECTED PLEASE PLUG IN TO CONTINUE...I install billion times the drivers and nothing is happening .Also i tried opening the laptop with not plug in the battery wire and sometimes it works..But rare...PLEASE HELP I NEEED HELP TELL ME WHAT STEPS I HAVE TO DO PLEASEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

THANK YOU