How to find deleted text messages

If you are using iCloud Syncing for Messages, once the messages are deleted, they are gone. There is no "finding" them.

If you're not using iCloud Syncing and you have a back up that contains the messages, you can restore your phone from that back up:

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Note that restoring the phone to that back up will overwrite everything currently on the phone.