In case you logged out and can't remember your login credentials,
- For Google+ account, please visit: https://accounts.google.com/signin/usernamerecovery
- For Facebook account, please visit: https://www.facebook.com/help/132243923516844
Please note that the login information are the property of Google or Facebook and we just can't help recovering those.
If you don't remember the account you used to play Flyff Legacy, you should try to login with all the Facebook and Google accounts you may own.