Facebook is an amazing platform to connect with your friends and family but every technical platform has some issues same with Facebook messenger sometimes users are facing that their messenger app not working. Without panic you can try the given solutions:
Update your phone
Uninstall and reinstall the Messenger app
Reset All Your Settings
Turn off Wi-Fi and turn it on again
Clear cache for Messenger
read also: https://ityug247.com/how-to-recover-deleted-messages-on-facebook-messenger/