[CentOS] sound problems... config?

The www has failed me with this, so I'm trying you guys.  Sound worked 
great out of the box when I installed 7.2... Yay!  I could watch all 
kinds of videos, like on facebook and youtube.  And I could listen to 
most podcasts too.  But then something happened. It was either a kernel 
upgrade or that I installed vlc (for watching videos on DVD) and the 
whole stack of codecs for it... I don't know exactly when, but at some 
point I no longer had sound with youtube  and other web videos.  The 
videos played fine, just no sound.  Note that using vlc, both video and 
the audio with it play just fine.  I need to select the audio driver 
(from a list in a vlc menu), however, else the sound won't work in vlc 
either.

If I go into the Applications menu, then System Tools -> Settings -> 
Sound, under "Choose a device for sound output:" there are no devices 
listed.  There used to be.

If I run "aplayer file.wav", nothing plays (no sound at all) and I get 
the error "main:786: audio open error: No such file or directory".  If, 
on the other hand, I run "aplay file.wav -D plughw:0" (i.e., specify 
the/a device), I do get sound, the file does play.

I ran alsa-info.sh and it posted tons of info from it on my setup at 
http://www.alsa-project.org/db/?f=1dba91886be054df4816000768a0f5b109947a48. 
Yet it still doesn't tell me what's missing.

Anyone here have an idea...? or thoughts about where to look next?

tia,
ken