There's this girl in my year, in my chemistry class that I used to get on with fairly well, we'd speak in lesson and I got on well with her friends too. One day, for no apparent reason, she just stopped talking to me around Easter last year(by that I mean she didn't even say a word and simply grunted whenever I asked her something). I tried speaking with her to ask her why but she simply ignored me, her friends still speak with me and have no idea either- even they say it's hard to figure out what she's thinking half the time.
Any advice would be appreciated...