Where has my confidence gone?

I'm a seventeen year old girl who used to get looks from many admirers, they'd stop and talk to me and when i went out shopping, people would approach me and give me stuff for free! wherever i went i'd attract people and i'd get either a wink or a smile. For a while, i was approachable, friendly and nice. I'm not sure what happened, but everything changed. All of that stopped and i've become quite afraid of new company and distrusting of people. i still look the same yet i feel i've taken a dip in the way i feel about myself. I used to grab an audience and just click with people, now i'm more reserved and i hate that. i just miss being happy with myself and my confidence, now i really care about what people think...Any advice?