why cant i pick up service anywhere?

[AC Question]

I cant get a signal anywhere. It is a ZTE maven z812 at&t go phone

 

[Rukbat]

Bring it into an AT&T Device Support Center (ask your nearest AT&T store where the nearest DSC is) - AT&T is pretty good at diagnosing problems. (It could be a bad SIM card - which they replace for free - and even a salesperson in the store can fix that.)