My Mac won't play audio at all. When I start the computer, it makes to boot up sound, but when I go to play music or turn the volume up it doesn't go anywhere. When I go to System Preferences and to "Sound", it says that "the selected device has no output controls. (By the way, I got the laptop from school)
Try plugging in headphones. A lot of people seem to have this problem when the connection is dirty. If that works, try cleaning it out.