We highly recommend you to link a Facebook, GameCenter or Google Play account to your in-game profile in order to secure the progress from loss.
If you discovered that your progress of the account is lost please login to the linked social network on your device and then in-game, go to the in-game settings menu and check the "Sync" option.
Unfortunately, in-game progress cannot be restored if you haven't linked your profile with one of the mentioned social networks accounts.
To sync your progress you have to link Facebook or Game Center/Google Play profile to your game account on your old device. You will need to login to one of the mentioned social network accounts on your current device. If the progress was not synced automatically, please, check the "Sync" button in the in-game setting of your in-game profile.
Synchronization of progress between different operating systems can be carried out only by linking to the game profile of your Facebook account.