I have installed ubuntu 10.4.3 on dell vostro 3550 laptop.
I have installed all files related to audio but audio is not working on this laptop.
From a reference on the ubuntuforums: http://ubuntuforums.org/showthread.php?t=1906905 some people have solved audio problems on this make of laptop by doing the following:
Add this line to /etc/modprobe.d/alsa-base.conf
Then, restart alsa by enter the following in a terminal session
If it is possible for you to do so it may be worth considering updating to 11.04 or 11.10, the Dell Vostro 3550 has been certified to work with both of these releases: Ubuntu Certification