Problems with a shy girl?

I'm in college, she's in college. We're both the same major. I knew her last Fall and saw her every day. She had a boyfriend then, but it was an online one I believe because she never talked about him and he's in another state. Over winter break, she became single again (somehow). I was only ociates with her last semester, and now in Spring semester she is in two of my cles. We sit next to each other. Slowly, I've been building up my friendship with her, but she is a ROCK. I'm moving as slow as I possibly can. I called her 7 times in 2 months just to chat a little bit. Every single time, she never picks up the phone nor returns my call when I leave a message. But I see her texting in cl from time to time. I thought things would change when I gave her a nice valentines card and heart shaped chocolates on Vday. Nothing happened, we didn't even hang out. So the past few weeks I've been asking to hang out with her not as dates or anything. But just as friends. I asked her to the movies, she's got homework. I ask her to dancing, she has a project due. I ask her to a party, she's sick all of a sudden. I ask her for coffee, she needs to run errands. My friends tell me to forget about this girl, that she's nothing but heartache and I'll never get her. I want to prove my friends wrong, I want to know if there's a chance something can happen. Please help a nice guy out. I need to know what to do now.