1) Work up the courage to talk to your friend again. It may be intimidating and you have to be able to face your fears and try to resolve the problem. (It's okay to cry, feel depressed. Even want to never talk to the person again, do try. These are all normal reactions to a fight. You just have to realize that you want to be friends again and want to try to resolve it)
2) Do not focus on your friend's weak points or negative side. Instead, do consider thinking about your friend's strong, positive points and side. Remind yourself why you became friends in the first place.
3) Make contact with the "friend" you have been fighting with. It's best if you can meet up with your friend in person. However, if they refuse to see you, consider phone, email, or IM.
4) Ask your friend why he or she is acting the way he or she is. Ask him or her if you have done anything wrong that you can fix. Talk to your friend until he or she can tell you exactly why you are fighting and he/she might apologize. Do not be afraid or too proud to say you are sorry too.
5) Work it out. Keep your friend talking. Don't let him or her leave the conversation until you have resolved your issues. Then see your friend as soon as you possibly can and tell your friend you love him or her and to be friends once more.