without knowing the exact reason for what your son was thrown out i cannot give you a correct solution. first you come to know for what reason your son was thrown out.ask him to realise his mistake and confess on that mistake.that will give an inner happiness in his mind.then slowly you set his mind to go to another school.

There must be some reason behind it, that he was thrown out. And now he is reluctant to go to another school or this experience might have some negative effects on him. You as a parent hold responsibility and need to talk to him and communicate efficiently with him, which is alas a long forgotten art i.e., Communicating With Your Teen Child. I want to quote some lines from a blog "Many teen problems start in their own home, unfortunately many parents won’t admit that, so they blame it on the school, teachers, friends, but in the end parents need to take most of the responsibility. The reason why that is a fact is because parents have forgotten how to communicate with their children. As our kids are now part of the internet generation we were once a part of the MTV generation and we cause troubles for our parents, but they knew how to deal with us more or less, that bond and that knowledge seems to be disappearing.
Communicating with teens has always been a problem, but it’s something we must do in order to be apart of their lives and in order to help them when they need it."
So the best thing is make your teen comfortable with you so that he can relate any problem arising and you as a parent communicate and listen to the needs of this 21st generation teens.

Remember that YOU are the parent.  Don't allow your CHILD to tell you, the PARENT, what he won't do!!  Also, there are counseling programs available.  Have you tried One to One Mentors?