How do I retrieve my boat from a business that closed.

I made a deal with a business that he could have the motor off my boat if he installed another motor that I supplied. I went lower on horsepower. He aggreed and now his business is closed. I have tried calling him and always left a message but he wont return my calls. My boat is outside and the work is not done. I just want my boat back now. Thanks for a response back.