Sound not working

Yesterday, I installed GNOME ALSA mixer to unmute HQ so I could listen to my headphones on my Macbook 5.1 for Ubuntu 9.10. The headphones worked perfectly when they were plugged in, then when I unplugged them, the speakers built into the Macbook worked perfectly as well. But, when I turned on my computer today, it started up with the normal Macbook sound, but when I went to listen to music I couldn't hear anything. I tried plugging in my headphones and didn't hear anything. I went onto ALSA mixer and didn't even see HQ there anymore, but I unmuted everything anyway... It still didn't work. I resarted my computer and tried this process three additional times; yet it still didn't work. I also don't know which box to check on ALSA mixer for sound... IEC958 or IEC958 Default PCM. When I pick the first one, there is a red light in the headphone jack.