Please contact our tech support team via the Support button in the in-game settings.

Try to provide as much information as possible. For example, did you lose any resources (event keys, purchases, or Gems)? Do you play on one device or several? Have you tried synchronizing your progress between several devices? Which mine had you reached (share the number of the mine or the main event) before you lost your progress? Also, attach a screenshot showing your current progress.