Open Facebook Messenger and check the Archived Chats folder
Search the conversation name or keywords in Messenger
Check the Facebook Download Your Information tool for message copies
Review email notifications if message alerts were enabled
Check other devices where the conversation may still be logged in
Ask the other person in the chat to resend the messages or screenshots
Check linked Instagram messages if the conversation was cross-platform
Look in phone backups or cloud backups if Messenger data was saved
Check notification history on Android if message previews were enabled
Use Facebook support only for account access or data download issues