In the absence of a written contract and no knowledge of which state this project is located in, I will assume an AIA short from of agreement calling for litigation exists. The contract is between a contractor and owner and all prerequisites to foreclosing a lien in Florida exist.
First, find a competent Board Certified Construction Attorney. If you don’t want a lawyer, I still have a few suggestions. Second do an asset investigation of the creditworthiness of the other side. If the defaulting contractor is penniless, kick yourself for going to work with him before checking him out. Next, find out if the property improved has any prior encumbrances. Was your lien transferred to bond? If not, a foreclosure may be the best option. If there is no first mortgage, you should reach out to the Board Certified Construction lawyer again. If there is no equity in the property, please, notify the Construction industry Licensing board of the nonpayment. Fifth, if the sum is small enough, go to small claims court and obtain a judgment. Thereafter, record certified copies of the final Judgement in every county you think the debtor has real or personal property. Finally take the debtor’s deposition in aid of execution. Start seizing assets via a writ of execution.