No Sound after installing Ubuntu 12 along side Windows 8

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http://askubuntu.com – I am a total new comer to Ubuntu. I got a LiveCD from Ubuntu.com and did the install. Installed Windows 8 on one partition and Ubuntu on another. After the install, everything is great and I am enjoying the OS, except when I play a YouTube video, I get no sound. Now I realize I am not getting any sound from either Ubuntu or Windows 8. Please help me. (HowTos)