My middle kid lost a magicband the day before we were supposed to leave. We don't even know how it happened, since everyone had their bands when we got into the hotel room the night before. Somehow, that one came off, and *POOF* off it went to the wild blue yonder. We never found it again, even when cleaning the room to check out.
We went to DAK's guest services the next day (I don't know why we didn't go to the POR front desk, but, meh). They gave us a Key to the World to replace the lost Magicband, and all was good.
Point is, even if you lost your Magicband, as long as you have your photo ID, a CM with account access can get you something that'll work.