It is possible to get a temporary DDE card. I would wait until Wednesday to call them.
1. Call the DDE office at 407-566-5858 between 8:30am and 4:00pm Monday to Friday (except Holidays) and give them your name and the fact that you have lost your card. You will be charged $25 for the replacement.
2. Starting at 5:30pm that day, and any time it is open, you can go to the Guest Relations Window outside Epcot's Main Entrance (On your right as you face Spaceship Earth) with a photo ID and you will be given an envelope.
3. The envelope will have in it a temporary card which expires 30 days from the date of the request and a sheet of paper listing all locations which currently accept the card. You will receive a new plastic card in the mail within a month.
4. I would suggest considering when the card expires as it might be more worthwhile to just get a new one, with a new expiration date, rather than spend the $25 now and then the renewal price in the near future.