Sorry to hear that. If you accidentally delete or lose text messages from your iPhone, you can use iPhone Data Recovery software to get back them. You can use it to scan your iPhone deeply and find the deleted text messages. You can preview them and recover them from iPhone to computer.
Here is how to do that:
1. install and run this recovery software on your computer
2. connect your iPhone to computer and scan it with this recovery software
3. preview and recover deleted text messages from iPhone
You can learn more details about how to recover deleted text messages on iPhone. Besides text messages, you can also recover deleted iMessages, Whatsapp messages, videos, photos, contacts, voice memos, calendars, notes, reminders, safari bookmarks and many other deleted files from iPhone easily.