Hi Robert,
Unfortunately there isn't a way to recover the deleted messages. Going forward, I would recommend backing them up with
RingCentral's Archiver, which backs everything up to a DropBox account. In the future they'll be adding additional cloud storage services as well :)
I'm confused. Shouldn't these text messages be backed up to your iCloud or iTunes?
Well, if you haven't got any backup, you can try a third-party program to retrieve the messages.
What I'm using is Joyoshare
iPhone data recovery Mac. It can recover the messages or photos in apps without overwriting the current data on my phone.
