I ran through the troubleshooting at https://help.ubuntu.com/community/SoundTroubleshooting
It did not play the test sound, and it also does not play sounds during
speaker-test. It does play sounds when I adjust my volume on my computer (using
pommed). It worked just the other day, but this is the first time I've tested it since last night, when I put it to
pm-suspend-hybrid and it half-woke up (the backlight came on, but it didn't fully wake up), then went back, then half-woke again, but was frozen like that. I had to do a manual reboot of the machine when that happened. Now my sound doesn't work, except for adjusting the volume (where the little "beep" sound plays).
During the troubleshooting, it recognized my sound card, the sound modules, and the sound card's installation. I've tried removing
~/.pulse, but to no avail.
Also, if it's any help,
pulseaudio is running, but
pulseaudio --check returns nothing, which the manpage suggests indicates an error.
Edit: I should probably clarify that the wake up from the suspend-hybrid was not provoked in any way. I was laying in bed when I noticed my room was brighter suddenly, so I got up to check on it.