With respect to your sound problem. It is almost certain that there is nothing seriously wrong. From what you have already told us it is clear your sound card has been detected and a driver installed.
The problem is likely to be either :-
1/ Sound is working but muted as I mentioned in my previous post
2/ If your motherboard has two sound cards it may be trying to use the wrong one.
3/ It may be trying to use the wrong output on your sound card.
To check out all of these possibilities a good place to start is the Pulse Audio Volume Control in Menu>Sound
Pulse Audio provides a volume control for every active sound application. So if you start playing some audio the 'Playback' Tab in Pulse audio should show a moving level bar for that source.
The 'Output' Tab of pulse selects which physical output port the sound is directed to. Check the options available.
The 'Configuration' Tab of Pulse allows you to select which sound card audio is directed to, and the configuration options for the sound card.
It is likely that playing with these options is all you need to do.
Have fun
