I lost all my confidence and i need to get it back...help please!!?

1st of all i dont mean to brag about any of the stuff i say.ok so at my old school(middle school) i was really popular. it was a small cl like 60 kids or somethin. there were like for guys who were really popular and i was one of them. the other 3 were my best friends. alot of girls have told me im really cute but ive always been kinda on the shy side. dont get me wrong i wasnt shy until it came down to doing something(makin out, etc.) I had a lot of confidence, but still was shy sometimes when i was at a dance or if i had to kiss some girl for a dare or something. I had a lot of friends and i was happy. now im a sophmore and im in a much bigger school(300 kids in a cl) personally i think ive gotten better looking just because i got taller and am a little mor muscular so i dont think thats the problem. but for some reason im not popular and i dont have any confidence. im becoming depressed bcuz i dont know wats wrong with me. Please tell me how i can get my confidence back.