Facebook Friend Trouble?

[Sir Justin]

For some reason one of my friends doesn't show up on my friends list anymore, and according to facebook, she no longer exists. But she does cause my friends can see her on facebook, just not me. Now I never blocked her, and she said that she doesn't remember if she blocked me or not. On the face book privacy settings on both of ours, it says that we do not have each other on a block list. Has anyone ever had this problem and do you know how to fix it?