This thread is in place to help those who have lost files due to an accidental deletion, or format. Cell phones use flash memory (typically micro SD). If you lose your files, you need not worry, they can be recovered.
This guide is for recovering deleted text messages from Android phone with FORecovery Android Data Recovery.
If you have lost your messages, you will need to contact your service provider and request them to resend them to you. Carriers keep copies of all messages sent and received on their servers for legal reasons. Say the police believe the phone is being used to take orders and traffic drugs. They would obtain a warrant, and the phone company would issue copies of all the messages.
This is only in place for legal reasons, so you need not worry about someone reading everything you say in your messages.