I installed Ubuntu 9.10 x64 recently. Up until now I've been on 32 bit Ubuntu. For the first time since installing it, I went and tried to play a Youtube video. There was no sound. So a quick test to the system reveals that nothing will play sound (And I've tried turning the volume too full, as some have said output is quite quiet, but there is no sound at all). Further research shows that in sound preferences, the only output device listed was Dummy Output.

Why would it work in 9.04 x86 and not 9.10 x64? While booting up, and occasionally with the sound preferences dialog open, I get a loud click (even though it isn't recognising my sound card).

It's a Dell Studio 17 laptop. I'm not sure what the exact model of sound card is.