I'm running Ubuntu 12.04 LTS on an HP G60-458DX. When I installed Ubuntu, all my audio outputs (HDMI, Analog, Digital, etc.)would show up under Sound Settings. However, recently, all these have disappeared. Because of this, Ubuntu won't let me control output volume. However, applications can and do still play audio through the built-in PC speakers, and their volume controls still work. This happened around the same time I first installed Pulse Audio Equalizer and first plugged my laptop into an external HDMI monitor/speaker system. At that time, all audio features worked as intended. Ever since then, I've had these listed problems and audio no longer plays out HDMI; instead it still plays from the PC speakers. I can control the sound on the login screen, but not once I log in.
Why won't my audio outputs appear in Sound Settings, but my PC speakers still work? More importantly, how do I fix this?