Buyer backed out of real estate urchase

The response assumes a written contract exists because sale of real estate, to be enforcable, it to be in writing. If the standard PAR form was used and the box was checked that permitted the buyer to walk for any reason, or none at all so long as the hand money was retained by the seller, then NO, there is nothing to do but keep the hand money. If the box was not checked, or it was a different form without that option, then you may be able to seek specific performance and force the sale, but you will need to hire a lawyer and sue.