I never take an apology seriously that doesn't specify what the person is apologizing for. The blanket "if I did something" is a complete cop out, meaningless. You know what you did. Name it and if you are sincerely sorry you did it - say so. If not - save your breath. If you meant to do what you did, but you still want to repair the relationship, say something like - "I realize our relationship was damaged when I _____________. I miss you, and I'd like us to try to repair our relationship. What can I do to help you feel better about me?" Good luck.