If you mean they have been deleted? They are gone unless you have not synced to your computer since you last backed up those messages. If they are in your backups, you would need to restore your phone but you would loose anything since that backup.
For service or support questions including existing order status, call: Customer Support: 1-800-331-0500
Information on iPhone unlocking can be found here by copying this link into your browser: https://www.att.com/deviceunlock/client/en_US/