Apply for a replacement card. If you are in the U.S. , you should be able to do this online, otherwise any Padi Centre/Instructor can arrange this for you.
As long as Padi received your original certification or you have proof of your training (logbook or temp cert card), Padi can issue a replacement. If there is no online record, contact Padi by phone as your original record may have been incorrectly entered into the database.