A canceled hotel reservation can occur due to a variety of reasons. It may be that they never had the reservation in the first place, or they are overbooked and have decided to bump your reservation. Either way, you need to be prepared in case this happens to you while on vacation.
Show all paperwork that you have that confirms the hotel reservation. Keep all confirmation numbers and receipts with you when you attempt to check in. This information can help the hotel track down the problem.
See what they have to offer. If they do not have a room available, see how they can help you get a room for your stay. They may have a nearby sister hotel that they work with.
Call other area hotels to see about availability. If the hotel can't help you, request a phone book and start looking for other accommodations.
Ask for the hotel to arrange your transportation to the new accommodations. If you do need to move to a new hotel, request that the front desk not only transfer you to the new location, but cover the travel expenses as well.
Write a letter of complaint following the trip. Address it to hotel management and let them know about the canceled hotel reservation. They may suggest that you stay at their establishment again for free or at a discounted rate.