The easiest way to apologize when you don't see the person. Write to friend in social networks, or send a text. Start by asking forgiveness. Then tell me why you behaved so, what prompted you to go into conflict with a friend or offend her. Then explain that you really value your friendship and want to reconcile. If friend is willing to forgive you - she will reply.
Ask mutual friends to reconcile you. Let them tell the friend that you are very sorry about what happened and ask for her forgiveness. Let friends remind her how long you were together and how having a good time. Let them tell that you are very worried, but afraid to talk with a friend, so you're embarrassed to look her in the eye. Most likely, the friend will like these words and forgive you.
If the letters and entreaties of friends do not help - have to decide on a Frank conversation. The phone is not the best way. Friend may be busy or not ready to talk. Try to meet her. Let friends invite you for a joint party. In the atmosphere of General relaxation serious conversation will be easier.
Apologizing to a friend explain his behavior. If not, it can only superficially forgive, harboring a grudge. Be sure to promise that you will never be so much around her. Tell me what your friendship means a lot to you, and you have no idea how you will cope with everything without the support of a friend. Sincerity will help you reach her heart. Friend will forgive you if they see that you have indeed repented.
Asking forgiveness of a friend, not to mention about the quarrel, speaking only of reasons. Memories of the conflict will cause only negative emotions that will prevent you to build a constructive dialogue with a friend.