ubuntu 10.04 (Lucid) no internet sound

[Moly Guinea]

I just upgraded to ubuntu 10.04 LTS. I can hear sound from sampling at Ubuntu One music store, but there is no sound when playing Internet video clip(Firefox).
After running the following suggested commands from Launchpad question post, I have lost ALL sound (not even login sound, no system test sound, no sound from earphone either):

sudo apt-get --purge -y remove flashplugin-installer flashplugin-nonfree flashplugin-nonfree-extrasound gnash gnash-common mozilla-plugin-gnash; sudo apt-get --purge -y autoremove; sudo apt-get clean; sudo apt-get update; sudo apt-get -y install flashplugin-nonfree

Close ALL browsers then retry the flash content.

Please help

[Moly Guinea (molyguinea)]

I have fiddled with the problem for a month, but with no luck.
Also i don't see any "ALSA" selection in my new sound preference panel in Ubuntu10.04, even though I had ALSA with Ubuntu 8 version (and it ran very well).