NEED GIRL ADVICE...This is killing me!!!! :/?

Ok so Ive really liked this girl sense high school which was 3 years ago. She is a year older than me. My Senior year we started talking and we both liked each other, but there was a situation later in the school year, and she ended up going out with a friend of mine...I took her out on a couple of dates but never really talked about a relationship...I was pretty upset cuz I was going to ask her that day after her softball game...I eventually got over that and she started talking to me again( this was about the same week i was going to graduate). I talked to her threw out the summer and we started hanging out again...Then she just stopped talking to me randomly...I though i got over her till i saw her like 6 months later and she talked about us hanging out again so i got all excited for that but then she never replied to my texts or facebook messages. So anyways Like 6-7 months ago I couldn't stop thinking about her, so i texted her and she actually replied and i tryed hanging out with her but she started ignoring me and every once and a while she would act like she never got the other messages. and when I asked her about it she denied all of it...She texed me the other day saying i dialed her...my phone says I never called her, and i was texting her for a while and she said we should hang out over the summer...Now i cant stop thinking about her...I haven't seen her in 6 months and idk what to do...My Friends say im Like this cuz shes the one girl that ive always wanted to go out with but never can....IDK WHAT TO DO...I need advice, :( sorry this is so long i just don't know what to do... PLZ HELP!