If you are playing on a mobile device, please make sure that the Facebook account you use to play the game with is logged in. If someone else has used your phone to log into Facebook on your mobile device, the game may have logged you out.
Also, we are able to save your progress and your Jewels into our server and restore it back if you played while connected to Facebook. However, if you don't connect to Facebook or play the game offline, your progress will be saved locally (on the device) and will therefore be lost when the app is changed. We strongly recommend connecting to Facebook to ensure your progress is always saved.
If you are playing on a computer or the above does not apply, please contact our support team about this issue.