Just about the same question was on allears:
Question: I put my AP away somewhere to keep it safe and now I can't find it. Does that mean I'm out hundreds of dollars? --OR-- I have ruined my AP/PAP by putting it in the washing machine. What can I do to get it replaced?
If it was an activated AP/PAP, you have no problem. Simply bring your photo ID to any Guest Relations location and they will reissue your AP/PAP to you.
If you have misplaced a new unactivated AP/PAP voucher, then you have a bigger problem. There is no buyer identification associated with a voucher. It can be exchanged and used by anyone. Your best protection from this is to make a photocopy of the back of your voucher as well as a photocopy of the sales slip and keep them where you would keep other valuable personal papers like insurance policies or bank books. You will have to prove two things to Disney in order to get it replaced: that the voucher actually existed and that you were the one that owned it.