Why don't I have friends? Please please help?

I've been in the same school since kindergarten, now I'm a sophomore.
I'm 15,
-last summer-
I was extremely popular and I guess it's just an sad change to go from having 3-7 close bestfriends and being texted by everyone and spending so much time with people and at sleepovers, and in having dinner after games and church.
-now-
I have zero friends besides when I'm at school and when I'm at school I have friends. Three guys text me l the time , I never get invited anywhere, ever. Even by the people who say we are friends. Basically everyone is fake to me now.

I don't know what I'm doing wrong, I don't cuss or do anything that isn't ladylike . Im clean and wear fashionable clothes, smile and laugh with everyone else, oh and I don't talk bad about ANYONE at all, my four bestfriends last year never invite me anywhere but are always together.
What have I done wrong how can I have atleast one friend?