"Face the music" is an English idiom describing somebody who has to deal with negative reactions to and consequences of something that he or she has done. Another way in which the phrase is used is to describe someone who must take on a difficult situation. The origins for this phrase, as with many idioms, are difficult to pin down. Part of the reason for this is that the figurative meaning of "face the music" is at odds with what the seemingly pleasant experience of actually turning to face music that is being played.
There are many occasions when phrases and sayings take on different meanings from their literal definitions. These brief phrases, which help express the abstract and metaphoric qualities of human thought, are known as idioms. They are colorful expressions that gain meaning over time from the way they are used in the culture. One such saying that has been in evidence since the 19th century is the idiom "face the music."
If this particular idiom is being used, it often means that someone has done something that was either improper or incorrect. As a result, the action that was committed carries negative consequences which the person ultimately has no choice but to face. For example, consider the sentence, "You were the one who stayed up so last night, and now this morning you have to face the music." The implication is that the person is tired in the morning, a negative consequence of staying up so late.
There are some occasions when this phrase is used for people who haven't necessarily done anything wrong. On these occasions, the idiom tends to indicate that the person being described is facing a serious situation or a moment of truth. In this context, someone might say, "We've avoided this night for as long as we can, but now it's time to face the music." This usage implies a big event with an uncertain result that must be faced.
Oddly enough, there seems to be some disconnect between the accepted meaning of the phrase and what it would mean if it were taken literally. It would not seem to be a daunting occasion to literally "face the music," since most people enjoy music. Since the origins of this phrase are uncertain, there is no way to tell at what point the idiom gained a seemingly imposing connotation.