Ok, thanks for the info. If you're only playing on 1 device I'd contact Support ASAP. S8 Support: Click here to contact S8 Support.
I've posted in thread for additional help for you on this.
If you switch between the same game on different devices and you are not on the most up to date version of the game on both devices, it can muck up your lantern count. It does fix itself when you log back in to the highest account. If this is not the reason, you should contact Support.
Maybe if you told me more about what was happening to your game, like has it always been zero, or what were you doing when it reset, or what device you use and what game version you're on - I could help you.