we are all different people so conflicts are expected especially with friends regardless of how close you are to each other. talk to her, communication is the only key here.

why bother if you really didn't do it? it's up to her whether she believe you or not as long as you have clean conscience.

explain your side and if it doesn't work, then think of another way until you get her to believe you.

how much does it affect you? is this a close friend of yours?

As what the saying goes: " never explain yourself to anyone, because the person who likes you doesn't need it and the person who dislikes you won't believe it". So just leave it alone, time will come and she will realize what she had lost.

Maybe you're thinking that it wasn't your fault but you just didn't notice how much it affects her. You have to keep the communication open.