I've been looking around for a solution for this, but didn't found it.
I remember that from USB (Live Session) Ubuntu had all its sounds. But after installed and after login, desktop-login sound never play.
I've been looking at dconf-tool without success. Any idea?
Best Answer
Rather than deleting the whole .dconf folder, just open dconf-editor and navigate to:
Change the value of "theme-name" to "ubuntu"
Also check to make sure that "GNOME Login Sound" is checked in "Startup Applications".
I've also filed a bug about this: