Can my parents break up my boyfriend and myself, claim I stole their car, take my check, and throw away my possessions?

I am 22 years old and live at home with my mom and aunt. A few months ago, they said that my boyfriend and I are broken up and that I am not allowed to ever see him again. Can they break us up and threaten a restraining order against him so he can't see me? This past weekend, I took my parents' car and drove to Maryland, but told them I was parking at a friend's house while I took a bus to a convention. I got into an accident and we are waiting for the results of that. If I call the police on them not allowing me to leave the house, can they turn around and say I stole their car? My parents have decided that my stuff is childish and stupid and that I have to stop dressing like a freak. They say they are going to throw it away and that I have no control because it's their house and they can do what they want. But it's my possessions, and as far as I know, it's illegal for them to do so. Can they throw it away just because it's their house?