Oops, it can happen of course. The first priority now is that you can continue to sell tickets. There are two options for this.
Use the receipt printer
At the cash register, go to Settings → Printer and temporarily set your ticket printer to the receipt printer hardware. From now on, the tickets will come from the receipt printer. Obviously this is not the ideal situation, but for now it at least means that you can continue to sell.
Let customers download tickets via customer display
At the checkout, go to Settings → General. Under 'Ticket issuance', select the 'QR Download link' option. Customers can now scan a QR code via the customer display to download their tickets.

Please contact us
Whether these solutions work or not, you are in no way in the ideal situation. So be sure to contact us and we will help you get everything working again.