How Do I Become Popular!

In year 9 i was popular i had all the friends i wanted, and people went out of there way to talk to me and i felt really good about myself. I went out alot and new everyone. Then i got into year 10 and the 2 sides of our year group mixed together and i found myself falling into the less popular group. Now most of the people i want to hang around with are in the popular group and i no thats where i belong but i cant get back in. I get on with every1 from the popular group but whenever a house party goes on i never get invited and i feel like i neevr go out anymore

Please help !!!!! xxxxx anon from england