Have you checked your bank account to confirm they did actually withdraw the funds? If they cancelled the ticket, the first thing that would come to mind for me is that there is some type of problem with the payment method and the payment, for some reason, had been declined.

Other than a confirmation number, were you provided with a ticket number? In the U.S. it's important to have that ticket number as a confirmation number alone is not sufficient to fly, and I would think it would be the same in Europe.

If you can't resolve this with Ryanair after the fact, your next route would be to deal with a regulatory body there that handles airline disputes.