Sound problem with ubuntu 8.04.1

[Sérgio Neves]

Hi,
I have ubuntu 8.04.1 installed.
Until yesterday, the system was well configured, with alsa enabled. But I 
damaged it when I thought on playing with the checkbox of service "sound 
management (alsa-utils)", on menu system -> administration -> services.
Since this, the system no longer produces sound.
With the help of my braille display, I've did what I know (which is not so 
much) to restore it: I enabled the same checkbox, went to 
gnome-volume-control and checked and unchecked the mute buttons, went to 
system -> preferences -> sessions and enabled and disabled pulseaudio, went 
to system -> preferences -> sound and put all the items to pulseaudio and 
after to alsa, restarted the system some times, but it continues without 
sound.
What can I do to restore alsa? Or where can I found a tutorial with 
information about it to solve this problem? I wouldn't like to reinstall the 
system just because of a sound problem (it is well configured and working 
stable).

Thanks
Best regards

Sérgio Neves