I recently lost many system and game sounds; codec packs didn't help (be wary of those, they may cause more problems than they cure), nor did "ffdshow", newer audio drivers, or numerous other "cures". Here is an excerpt from my thread on another site, the problem wasn't missing codecs but corrupt registry entries for the codecs:
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I had done a system restore to before the IE update, but the sound problems remained (this "update" had also necessitated me reinstalling the vid drivers and the drivers for my force feedback wheel). My wave editor (Adobe Audition) had also stopped working ...until I changed its I/O from wavemapper to Creative "what you hear", this proved to be the critical clue.
Researching the lost wavemapper, eventually I found several threads concerning lost sound in flv playback in which the most common solution was a registry edit - there was even a reg file to d/l to correct this. This had no effect for me so I tried to manually edit the registry; the required lines were not present and the registry wouldn't let me add them, claiming they already existed.
Ultimately I found the solution: a bit of Vista idiocy required me, as administrator, to give myself, as administrator, permission to access that part of the registry (I'd been editing other registry areas for ages). Once past that vicious circle of ownership, permissions, and access, that section of the registry appeared and I was able to apply the reg file. All sounds are back, changed Audition I/O back to wavemapper, and the system seems normal again.
http://www.mydigitallife.info/adobe-flash-no-sound-wavemapper-trick/http://www.geekstogo.com/forum/topic/251299-no-sound-on-youtube-etc-wavemapper-m...