I've been looking around to see if anyone's had the exact same problem I'm having, but I haven't seen any.
Here's what went down:
I recently upgraded to Windows 7 from Windows XP SP2 and voila--no sound.
The lil speaker thing in the taskbar has a red "X" on it and a message that says there are no audio output devices installed. Well, I checked Device Manager and viewed Sound, Video, and Game Controllers for any sound drivers and they're there. Installed correctly.
I've tried many fixes that have worked for others: Disabled then re-enabled the driver; un-installed then re-installed; checked for hardware changes; updated the driver software (it was already up-to-date). None of it worked.
I used to have a driver named "Realtek HD Audio Device" before the upgrade, but that no longer seems to exist. I think I need a UAA High Definition Bus Driver, but my attempts at getting one didn't work.
If that's not how to solve this problem, does anyone else here know a way?
EDIT: I should probably also note that recording devices work...It's just the output sound/speakers that aren't working. I dunno if it's just that an HP Pavilion Slimline s7415c can't fully support Windows 7 or if it's just Windows 7 being stupid since it seems to give a lot of its users problems regarding sound.