My mob is c3-00 nd wen I open my mob camera it says opertion fail bt wen I chnge to phn mem it works

Your lack of complete words hurts my brain, and how is that a question? I take this to either mean your phone's camera app only works when you are in the phone's memory (in which case, you might want to talk to your distributor about that) Or, your camera that your mob of 300 people stole isn't working.