How come my Toshiba lap top's built in Webcam doesn't work?

I have a Toshiba laptop that i bought about a year and a half ago and when i first bought it the webcam worked perfect. Now when i need to use it, it wont work and it is getting me frustrated! I have no idea what to do. I believe what happened was i had some problems with the computer and it deleted everything i had and im pretty sure it deleted the webcam software.