If the property is still in your name, you owe the taxes to the city or country (whichever government assess property taxes where you are): the property owner owes the taxes. You could sue the buyer for the money you have to pay, since they violated their obligation to transfer the property to their own name; of course, if you can't find them, you can't sue them, and even if you know where they are, if they have no money, there's no point in suing, since you'll never be able to collect from someone who is insolvent.