Don't cancel yourself . You sould contact Airbnb asap. about this issue.
On the confirmation email you will see a phone nr that you can call. or use Twitter @ AirbnbHelp. You are obliged to know who is in your home. Also: you should be able to keep contact with your guests through email, telephone and Airbnb. That's not possible now. Keep on trying to reach the person who booked by using al possibilities: email, Airbnb chat and telephone to ask for more information about who is knoming.