Sound gone with 9.04

[Sandy Harris]

upgraded Xubuntu 8.10 to 9.04 on a core 2 duo 4 gig box
Sound is via some on-board chip; worked fine in 7.04, 7.10,
8.04 and 8.10 with no significant messing about.

Amarok looks utterly different & no longer produces sound.
Testing with movie player, no sound there either.

How do I diagnose this? Better yet, how do I fix it?

-- 
Sandy Harris,
Quanzhou, Fujian, China