I'm not attracted to anyone anymore?

I'm just an average 16 year old girl going through high school. The only problem is I find no guys attractive anymore! I used to get head over heels for them, butterflies in my stomach, the whole package! But now absolutely nothing. I don't like girls so I know I'm not a lesbian, but I just feel so empty inside. I have felt this way for almost a year now..and i have never been in a serious relationship so I know that I'm not emotionally scarred. What is wrong with me?!