Difficulty: Moderately Easy
Step1
Sing a different song to yourself. It will probably knock out the original tune, and if the new one ends up also stuck, at least you've created some variation.
Step2
Sing the song aloud. Sometimes bringing the music out of your head and into the air will allow your brain to let go of it. On the other hand, it may make things worse.
Step3
Look up the lyrics on the Internet, if there's a section you can't remember. It's often the missing part that you obsess on, and completing the memory allows you to let it go.
Step4
Try to figure out the meaning this song has for you. Your unconscious has chosen it for a reason; the lyrics may refer to some repressed emotion that is ready to surface despite your resistance, or you may have heard the song in association with some event in your past. If you uncover and deal with the repressed emotion, your mind will no longer need to replay the song.