It's always the case that you or the person who borrows your phone might have pressed the delete button inadvertently or you could have made it happen by squeezing the phone when laying it inside your pocket. There're also strong possibilities that your text messages have been erased by erroneous operation of the system itself, your phone has been formatted or attacked by unknown, severe viruses, you have restored the factory settings, or your messages have been replaced by new ones due to the phone's capacity of containing only a limited number of messages.
If you recognize the necessity to retrieve the deleted text messages from your android phone, Coolmuster Android SMS Recovery will be the best choice for you.
And you need to root your android phone at first, or the app can't detect your phone successfully. And stop saving new data to your phone, or the deleted data will be covered.