1. Did “you” delete them?
2. Are you using the native Messages app or a 3rd-party messaging app?
3. Do you have
4. Is Messages enabled in the iCloud settings? If so, it’s possible to view those messages on another Apple product using the same iCloud credentials.
5. Have you tried rebooting your device to see if those messages reappear?
Before finding ways to restore or find back your phone number, you'd better stop using your phone.If you add new files to cover the deleted data ,it won't ba recover permanently.
And you can try 3rd party data recover program to find back.
It can scan all of your files ,including deleted text messages.