Look around the BIOS for any disabled USB or web cam.
Same for the Device Manager in Windows.
My Dell Insp 1545 has (had) a built in web cam. I used it often for skyping. One day it was there the next NOTHING. I got a message that said "please plug in supported device" i even bought a driver checker re placer thinking maybe that would help...nope. I even went back to the date all was fine, still nothing. HELP.