Why did my Daily Bonus reset?

Your Daily Bonus streak resets if you do not claim your reward before the countdown timer expires.

The timer at the top of the Daily Bonus window, labeled "Collect next day bonus in:", shows when your next reward becomes available. If the timer expires before you claim your reward, your progress will reset and your streak will start again from Day 1.

A reset Daily Bonus streak cannot be restored. Your streak will need to be built up again from Day 1.