I think my best friend doesn't want to be friends anymore?

If she doesn't want to be friends anymore don't chase her. Let it be up to her. If you chase after her then she will think you're weak and will keep doing the same thing. Give her a lesson. Don't do any contact with her. If you're near her try not to talk or give eye contact or any contact. It happened to me once and my friend ended up moving to California because her family lost their job.