What kind of phone are you using? Is it rooted? What rom are you using?
There is no info for anyone to go off of to start to help.i had similar issues on my galaxy s2 epic 4g touch. I had to fix permissions when i used cm10.1. When i switched to toiched by s4 i had two cameras neither worked so i tried fix permission again and accomploshed nothing. I downloaded an app called silent camera and i now have a working camera
Sent from my SPH-D710 using xda app-developers app