How to recover deleted texts

The only way to recover deleted text messages for the iOS device is to restore the device to a backup that was made when the text messages were on the device. If there is no backup, there is no recovery. Remember, that restoring a backup will bring the device to the date/time of the backup and anything done since that date/time will be deleted.

Use the instructions here, depending on the type of backup you created. Restore your iPhone, iPad, or iPod touch from a backup - Apple Support