Webcam isn't working in Ubuntu 14.04
Solution 1:
I think you should install UVC driver. You can get information on troubleshoot webcam issues from this link.Click here
Solution 2:
I also had this issue ... closely look at your keyboard to see if you have a multifunction key with a webcam icon ... for my keyboard the F6 key multi function icon looks like a webcam ... so I hold down the Fn key (often its purple) and F6 key to toggle on/off ability to use the webcam
ubuntu 14.04 and above comes by default with necessary drivers