Join Date:Joined: Feb 2011
It could be that your Camera Connector has somehow disconnected itself from your Phones motherboard.
Last month I had the same exact problem as you. After days of rooting, and flashing new roms, I decided to take a look inside my Nexus.
And I found that my problem was that the Camera Connector somehow came loose, so I reconnected it and my camera and the camera application came back.