@Lorraine182 It's up to the guest to ask these questions of Airbnb, not really the host. Why do you want to check if Airbnb has refunded their money? If it's cancelled, it's cancelled- does it show as cancelled on your end?
Airbnb will sometimes cancel a guest's booking if they were unable to collect payment, or this guest has been reported for illegal or objectionable behavior. So if that's the case, consider yourself lucky to have had it cancelled.
Or it could just be a system glitch, but it's in the guest's court to speak to Airbnb about this. They won't give you any useful information.