Open the Messages app
Tap Edit or Filters in the top-left corner
Tap Recently Deleted
Select the messages or conversations you want to recover
Tap Recover
Confirm by tapping Recover Messages
Restore from an iCloud backup if the deleted messages are not in Recently Deleted
Go to Settings
Tap your name
Tap iCloud
Tap iCloud Backup
Check the date of the last backup
Erase the iPhone
During setup, choose Restore from iCloud Backup
Select a backup made before the messages were deleted
Restore from a computer backup if available
Connect the iPhone to a Mac or PC
Open Finder on Mac or iTunes on PC
Select the iPhone
Choose Restore Backup
Pick a backup made before the deletion
Check other Apple devices signed in with the same Apple ID
Open Messages on the other device
Look for the deleted messages if they were not synced yet
Contact your carrier if the messages were SMS and backup recovery is not possible
Use a third-party recovery tool only if necessary
Back up the iPhone before attempting any restore process