First of all, make double sure that you signed into the Google Play (Android), App Store (iOS), or a Facebook account you used to start the game.
N.B. When you uninstall or reinstall the game that is not connected to Google Play (Android), Game Center (iOS), or Facebook, the progress will be lost.
If you are unsure whether your account was connected to the Google Play, the Game Center, or to Facebook, please submit a ticket and specify the nickname of your missing character.