did you try calling 1-800-DISNEY4U? that is the number on the back of the brochure i got with my card. surely they can look you up & reissue a new card. or do you mean you did this & there is a replacement fee?
I lost mine a few months ago and I called to ask for a replacement. They sent me one, free of charge. I think it came fairly quickly, too. Of course, I found the old card right after receiving my new one! Now I carry one in my wallet and keep one at home in the desk by the computer.