I had exactly the same problem. With the installation of Los I started to have the first camera issues. Firstly, it was just bad quality, then green stripes, then drop outs, now nothing at all.
In the process, i had done a complete revert to stock just for clarity. Nothing changed. The camera was gone for good...
I did some reading and it appears the back cameras of the earlier days have issues and are to be exchanged in case of any problems, no questions asked.
However, it also occurred to me that the constant flashing of different (beta) ROMs had its role in this play. Maybe some bad driver was just giving the camera too much juice for a while?
Anyway, once i return from my travels, i will have to get a replacement camera. Good thing is, they're pretty cheap and tutorials how to do it are easy enough to follow.
Gah, okay...I don't want to have to open it up because I'm sure it won't be waterproof after that, but if that's the only fix then I will