Why does my father prefer my brother?

I know, you are saying it is all in my head. I am 25 years old and still live at home, Kinda. When I was young my father was great! When I turned 14 he started distancing himself from me. I have a brother, who is 21, and he takes him everywhere with him, he says positive things to him, he lets him borrow money from him. Basically its like he has a son and NO DAUGHTER!! When I see him I am nice to him and say hi, but he doesn't answer or he answers rudely. There is alot more but, I would be writing all day. What can I do to make him Love me again?