There is a spare media pack in the side pocket of the case. Your package includes a set print count — 100 on the Canon tier, 400 on the Pro tier — and running out means you have used it.
Call (914) 825-5498 and we will tell you whether there is more in your kit. If there is not, the booth keeps working digitally: guests can still shoot and text themselves photos, they just will not get a print.
Didn't solve it? Text (914) 825-5498. If it's your event night, lead with that — those go to the front of the queue.