Should i ask her friend for help,or not??

[j.A.R]

There is this girl that i've been friends with since last year in highschool when i was in freshmen year,now im a sophomore.
Ps.the girl is one grade older than me she is a junior now.
So back then in freshmen year i got the opportunitie to be friends with her, so we started hanging out at lunch,talk on the hallways etc,i started gaining feelings for her then she found out by someone else telling her in class she didn't seem to bother,but after that she started getting really quiet like shy when i approached her to talk or hang out why did she get like that what happened,i got annoyed so we stopped talking.
Now i'm a sophomore and after a while i still like her even more but now i can't seem to talk with her nomore,there is this one other girl that is really good close friends with the girl i like so now i sended a request on facebook to this girl,but now thing is that when this girl sees me in school she sees me and looks at me for few seconds in a really serious expression,why.