You can file a lawsuit against him seeking both a court order that he turn the deed over to you and also seeking monetary compensation, such as the equivalent "rent" for this property for the time until he turns the deed over to you, on the theory that you don't have full legal possession yet and so he should pay you for the time that he still has legal possession. You file the lawsuit based on "breach of contract": on his violating his contractual obligations. There was an agreement that he'd sell the property to you, which includes turning over the deed to you, in exchange for you paying him; since you fulfilled your obligation (paid him), he is contractually obligated to fulfill his, too.