My besy friend turned her back on me? Help? ;(?

This year my friends and I are placed in different cles. We rarely get to meet each other. This one girl used to be one of my close friends last year are friends with other girls in my cl. We don't go to recess together anymore, she just leaves me as if I dont exist. I tried to get along with them but her friends are so damn snobbish. I can't believe my best friend left me just like this. It seems like I can't make friends with any of my clmates. What should I do? :(