Assuming there is no threat of physical violence, talk directly to the person with whom you have the problem. Direct conversation is much more effective than sending a letter, banging on the wall, throwing a rock, or complaining to someone else.
Choose a good time
Plan ahead and allow yourselves enough time for a thorough discussion. Don't start talking about the dispute just as the person is leaving to make dinner, for example. Try to talk in a quiet place where you can both be comfortable and undisturbed for as long as the discussion takes.
Think about what you want to say ahead of time. Explain what the problem is and how it affects you.
Don't blame or name call
Antagonising the other person only makes it harder for him or her to hear you and understand your concerns. Don't blame the other person for everything or begin the conversation with your opinion of what should be done.
Don't interpret the other person's behaviour: 'You are playing your music really loud on purpose just to make me mad!' Instead, give information about your own feelings: 'When you play your music loud, I get angry because I can't get to sleep or concentrate on my work.'
Give the other person a chance to tell his or her side of the conflict completely. Relax and listen; try to learn how the other person feels.
Show that you are listening
Although you may not agree with what is being said, tell the other person that you hear him or her and are glad that you are discussing the problem together.
Talk it all through
Once you start, get all of the issues and feelings out into the open. Don't leave out the part that seems too 'difficult' or too 'insignificant' to be important. Your solution will work best if all issues are discussed thoroughly.
Work on a solution
When you have reached this point in the discussion, start working on a solution. Two or more people co-operating are much more effective than one person telling another to change. Be specific: 'I will turn my music off at midnight' is better then than a vague 'I won’t play loud music late at night anymore'.
Agree to check with each other at specific times to make sure that the agreement is still working… then really do it!