My boyfriend took anything, can I win the case?

lived with my boyfriend for 6 years, have one 6yrs old son. 5 years ago, his relative wanted to rent a restaurant to us, he didn't have any money, so I gave him 20,000 dollars to rent it .so both of us work at the restaurant, we were signed as the restaurant signer, after 3 years we decided to take over the restaurant, and then we paid the whole amount to own the restaurant, His relative said, the procedures of changed the owner’ s name were too much, we all know the restaurant is your, so we didn't change the owner’s name of restaurant .Now ,my boyfriend and I broke up, he asked his relative to take off my name from the signer list, so I couldn't sign up anything for the restaurant, included the money in the bank too. I felt very terrible, what can I do? if I go to the court, Can I win the case?