What should I have done?

This situation I had today has a long story behind it and it involves this girl I met freshman year (last year) in college. Basically, I fell for her and tried to devise so many ways to approach her and I actually did a few times. The first time I did it solo and it wasn't too bad. Then it started to get worse after I got to many people involved, one person being a guy I knew that would be my wingman. He approached her in front of her door and chatted with her for a while. They got along. Now he wanted me to come with him and "re-introduce myself." I did and boy, did I mess up. She denied me and said she never met me. I actually kind of denied her too but, damn it was so awkward! Anyways long story short, in the end she told me to "back off." I did until today when I was taking the bus to the mall. I was sitting towards the window with a random woman sitting right next to me. She boarded the bus along with 10 other ppl but had to stand in the aisle as the bus was packed.