Clearly you're new to this. Your earnings didn't disappear. If you select the Earnings Summary and then change the month to January 2017, you will see the month's balance. Shutterstock resets the Earnings balance to zero at the start of a new month when you have reached payout.
Within a few days you will receive an email with the amount you can expect in your payout. Then a few days later you'll get a PayPal notification that the money has been received. Shutterstock says the money will arrive by the 15th, but it inevitably arrives much sooner than that.
This has been the process for more than a decade. Relax and enjoy the anticipation.