My sound broke on RHEL 6

Not sure what I did (I suspect it had something to do with rebooting while docked), but my laptop sound (and mic, I think) stopped working again. Unfortunately, this is one of those things that happens rarely enough that I can’t ever remember what to do about it. I usually go through the obvious on the little GUI sound prefs panel (twiddle output devices, test speakers, etc) which, in many cases, is sufficient to kick it back to working. However, that didn’t work for this one, so I did some googling and found a bunch of handy things. However, the one that really worked was In particular, going to the command line and running the alsamixer (alsamixer -c 0) which, for some reason, always shows me the actual output device that has magically gotten muted.