First, read the contract.
Usually towards the end of these contracts there is a paragraph on remedies available to the buyer and seller if one or the other refuses or fails to perform. Sometimes the contract will say something like "in the event the seller refuses to close or cannot convey marketable title, then the sole remedy to the buyer shall be the refund of the deposit". If it does not clearly state that the buyer waives the remedy of SPECIFIC PERFORMANCE, a properly filed suit can result in a court order either requiring the conveyance, or doing it itself. A suit in specific performance is NOT a do-it-yourselfer. You need representation by someone who does real property litigation. If you don't have a lawyer, either check with The State Bar of Texas lawyer referral service, or the lawyer referral service in Houston, or in one of the outlying counties if you live in the suburbs.
Another note: if this is a usual sort of real estate contract there probably is a prevailing party attorney's fee clause. This means that many lawyers will be happy to take a look at you situation, and, more than likely, set up an easy payment plan for you. If you win, you will get the property, and the court will probably order the reimbursement to you of your lawyer,s fees and the costs of the case.