To avoid any loss of progress make sure that you are signed into your Facebook account in the game or with your Apple ID (for Apple devices).
This will allow your game to be saved to the cloud and you will just need to download the save from the cloud when you:
- change devices
- reinstall the game
- use multiple devices
If you did not sign in to Facebook (or your Apple ID) prior to losing your progress we are unfortunately not able to restore any lost progress.