I empathize with your feelings............what is making you feel that way? Are your grades bad? If your grades are poor, it doesn't mean your not smart.....it just means that you learn in a different way than "they" think you should......I know all about that, trust me. Colleges are really good at making accomodations these days. There are all kinds of learning resources and disability services for those who would like to access them.
Are you being bullied? If you are, you should talk to a trusted adult in your school that can help you sort through it all.
Really go deep and think about what's causing your lack of motivation. You can turn it around, you really can.
I don't want you to throw your dreams away. You can do this!