Me and this girl were super-close friends. We may as well have been boyfriend/girlfriend. We'd always talk and spend time with each other, tell each other how we love each other, talk about our future together, and stuff like that. And then one day at my house, she tried to kiss me. We had done some stuff physically together before, but not kissing so far. I had never kissed anyone before, so I really wasn't any good and she didn't really enjoy it. Afterward she said that she would take our friendship down a notch (paraphrasing), that she didn't like being "the teacher" and me the "shy guy," and that she didn't want to hurt me or have any regrets. She also said that we can't go back to the way we were... We're still friends and all, just not as close as we used to be.

Problem is, I still like her and I really enjoyed the relationship that we had before we kissed, and I want to restore that. How do I fix this?

Just give her time. She's the "shy one" now not you. Kissing you made her feel that. I think she's just making it as an excuse. Talk to her, tell her that you loved the kiss. You should be the one who initiated the first kiss. Try it on your second kiss if you got the chance :)