Check the Messages app’s Recently Deleted folder
Open Messages
Tap Edit or Filters
Tap Show Recently Deleted
Select the deleted SMS
Tap Recover
Restore from an iCloud backup
Go to Settings
Tap General
Tap Transfer or Reset iPhone
Tap Erase All Content and Settings
Set up the iPhone again
Choose Restore from iCloud Backup
Restore from a computer backup
Connect the iPhone to a Mac or PC
Open Finder or iTunes
Select the iPhone
Choose Restore Backup
Check another Apple device using the same Apple ID
Open Messages on the other device
Look for the missing SMS
Contact your carrier
Ask whether SMS records or copies are available
Use a third-party iPhone data recovery tool
Scan the iPhone or an available backup
Recover deleted messages if possible