problems

hi my name is Barbara Frazier. My website is www.kingsandqueens.biz I signed a contract with someone who built my site and we have a disagreement. He registered my company name under his company which I did not know until I talked with someone about switching to their company for hosting. He knows said I owe him money to change the registration in my name. I told him I would take him to court because he is changing the contract. He also built the site (which I paid for) in such a way that no one else will allow it to be transferred to them to host.
What can I do?