Open the Messages app
Tap Edit or Filters
Tap Show Recently Deleted
Select the messages you want to recover
Tap Recover
Tap Recover Messages to confirm
Check if the messages are in another Apple device signed in with the same Apple ID
Restore your iPhone from an iCloud backup made before the messages were deleted
Restore your iPhone from a computer backup made before the messages were deleted
Contact your carrier if the messages were SMS and may be available through your account records