Yeah I had this same problem once. But in order to answer your question. Is the phone one of those pay as you go type cell phones. If it is then heres what I had to do. I called my service provider which is net10 and asked them for the code and after a few minutes of net10 searching for it they gave me the code. and it worked. So really you need to contact your service provider. Or contact LG.

This is just my suggestion