If you have already backed up your iPhone with iTunes, you can
recover deleted text messages by the following steps using iTunes:
Click the File menu and select Devices > Restore from Back up.
Or
Open the iOS device's Summary tab. There are two ways to access this:
Click the device button in the upper right corner. (If viewing the iTunes Store, click the Library button in the upper right corner. The device button will then be visible.)
From any view in iTunes, click the View menu and select Show Sidebar. Select your iOS device in iTunes under Devices.
Click the Restore Backup button.
If you haven't had time to back up your iPhone before the deletion, there are also two methods for you to try:
1. Recover the text messages directly using a third party software;
2. Recover the text messages under DFU mode.