How do I find my old account please
If you log in with the Apple / Google account what is used for playing that old account, then it should be loaded back.
If that is not works, then you can try to reach in game support about it.
Or if you can not log in to the game at all, then you can use this site where Support might be able to help you:
If you know your old Account#, then it would be helpful for support.