Try the lost phone trick to reset your account.
To report your phone stolen. Login to your account. Choose Plans and Add-onstab. Then choose Lost/Stolen Phone tab. The choose Suspend Service tab. Logout. Wait few minutes. Login in and report your phone found. if you still have problems then try contacting a moderator.
Moderator can be reached at
If you had a working account that suddenly stopped working.. .and you have tried your SIM in a different phone, I would message a MOD for help.
Also - just make sure ur billing is up to date.