Sudden frustration: a question for my friends in the Linux world.

[mapsedge]

I upgraded Ubuntu to the latest version, Jaunty Jackalope, and suddenly sound stops working. All of the physical connections are valid, the music is there, the volume is not muted - I keep it set at 80% or it overdrives the speakers no matter what the mixer is set on.

So, where did my sound go? If this was Windows, I could probably track in down. Linux? I don't even know where to start.