Audio quit working, help?

[Åndhrimnir]

My sister's (fairly new) system is running sound from the Asus P5N-D motherboard. She's got Windows 7 HP. Recently the sound seems to have stopped working. I played around with it and the sound seems to be okay - headphones still make noise when USB devices are plugged/unplugged and when I hit the 'preview' button in the sound setup panel (which plays a little test 'ding' sound). But DVDs, games, iTunes, etc. don't make any noise. Checked the simple stuff like whether those applications are muted in the audio mixing panel, but I'm out of ideas now. Anyone know what might have gotten changed?

EDIT: Ah, nevermind. She'd accidentally disabled the speakers as an audio device when changing the volume... idk why system sounds still worked though... anyways, it's fixed.