Ok. This was a false alarm. It turns out that the Beats Audio software on my computer was not working in Ubuntu since there is no Ubuntu version. Hence, when I updated Ubuntu, the local sound card activated and was able to provide me with sound.
As for Windows, the Beats Audio software was installed, but not running and since it controls the sound, the sound card reported to work properly, but there was no sound.
Solution to this problem: If you installed Ubuntu and you don't get sound, "the problem with Ubuntu might be that you are using 3.2 kernel (i.e. 12.04 or 12.04.1). You can upgrade to 12.10 or 12.04.2." as Soroosh129 pointed out above.
For Windows, check to see whether there is a third party application that controls your sound (in my case, it is Beats Audio), and configure it properly.
Thanks to you all for helping out.