Open the Messages app
Tap Edit or Filters
Tap Recently Deleted
Select the messages you want to recover
Tap Recover
Confirm recovery
Check if the messages were backed up to iCloud
Restore the iPhone from an iCloud backup that contains the deleted messages
Check if the messages were backed up to a computer
Restore the iPhone from a Finder or iTunes backup that contains the deleted messages
Ask the sender to resend the messages
Use a third-party data recovery tool if no backup is available