Welcome to LQ softfo!
Err...upgrading from 9.04 to 9.10 has left many here with fits, just search and you'll see.
Be patient as its probably either a bug or maybe a permissions issue.
so, in your 9.04 setup when you inserted usb a icon woud appear on desktop
and file manager would open on usb?
and now it doesn't?
are you using kde, gnome or what version of buntu?
if you open a terminal with usb plugged in issue command
does it show usb device?