If you're on iOS you simply redownload the game, unless you've restored your device, in which case if you have a backup (a computer backup, like you actually backed your device up to iTunes, not just iCloud), then you could restore from that backup. Android I believe RiliSoft says your progress should stay if you redownload the game. Amazon and Windows, not a clue, although I would think Amazon and Android would be similar. What sort of device do you use, if I may ask?