If you find your game to have started again from the beginning, it's very likely you connected the game but the game has disconnected from the service. All you have to do is open the game, go to the settings and connect using the same account. If successful, your previous data will load.
Our game works as follows. When a player plays the game without connecting to a social media (Facebook/Apple/etc.) account, they are considered a guest account. The data for the guest account are saved to the phone's storage. Players can delete and reinstall the game and it would not affect the data. However, the data can be deleted if the player manually deletes the game data files, deletes the game account, or reinstall the phone's OS.
If the player connects to a service like Facebook, the existing game data is then linked to that connected account and will no longer be saved to the phone's storage. If the account is disconnected or if the game is reinstalled, the game will start from the beginning again because the data has already linked to an account. Players will need to recall the account used to retrieve their data.