What causes girl to ignore a guy?

I goin to make this a simple as possible since my iphone froze in a long paragraph.

I like this girl. I know she knew liked her. But I guess she didn't want to let her self go… As in to send back the same responses. I though she like me or at leased considerd me. I not ughly and I was the best person I could ever been with this girl. I freckin walked to class almost every freakin day 10th grade year. Now she can't even say hi. This happened last week. She said hi on Monday and Friday i was a stranger sayin hi twice and walkin up with a blank stare and nothin. That was really awkward. I didn't know wat to do. I just left. I think she thinks I'm dating or getting at my felmale friend we hang out a lot and she good looking. Cause she just stopped talkin after she saw me with my friend walkin out of school. She was waving at some one her friend i not sure it was me since she never doses that to me ever and i though she could be jealous. She says hi to my friends and all, and not to me stupid Friday. I havnt talked to her since I havnt done anything wrong.

Give her space don't ring her or text her