[ubuntu] Can't recognize sound card/hardware anymore

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http://ubuntuforums.org – Hello, I just plugged my new 5.1 sound (Samsung ht-d350k) to my notebook (Sony Vaio VPCF115FM) optical out port. Things were going well, except for the fact it was playing like a 2.1 sound system. Unsuccessfully trying to make it work correctly, I downloaded and installed a new Realtek driver, which after installed, simply made my sound card disappear from the system. Now I can't get any sound reproduced, nor the sound card is displayed under the "Hardware" tab (System => Preferences => Sound) anymore. Therefore, any tip is appreciated!! I tried reinstalling alsa an (Hardware)