My LG CE110 (AT&T) says 'Service Unavailable' everytime I try to make a call?

[LizzyLubb♫]

All my other cell phones are working perfectly but my LG says 'Service Unavaliable' when I try to make a call. This is actually my daughter's phone and she admitted she was just pressing some things.
How do I fix this?
I called AT&T and they don't help because they want me to basically buy a new phone.
Thanks.
It's basically telling me to turn on the "wireless." How do I do so?

[Adios Mother F]

You could try a new sim card in the phone. That will most likely fix the problem.