If the deal falls through after the conclusion of AR, it depends upon the reason. If you are not in breach, the deposit is refunded. Sometimes, the buyer does not believe he/she breached a contract, but the seller thinks the buyer did. In those instances, the deposit is not released until the parties reach agreement or a court decides the issue for them. In most cases, the parties do reach an agreement.
If any of these are the reasons your deal fell through, you need to write a letter to the party holding the funds ( specified on your contract ) and request the release , the seller has to agree in writing and then the funds can be released. If you just changed your mind, you could be in trouble.