"No Audio Output Device Is Installed", but I HAVE installed one?

Hi, I'm pretty desperate for help with this issue, I've been searching on Google for the last three and a half hours for a solution but came up with nothing, so I thought I'd post here to see if anyone can tell me what's up.

I turned on my laptop today to find that there was a little red 'x' over the audio symbol, and upon further inspection it turned out that there was no audio driver installed. I wasn't very bothered about it at first, because after a Windows update once I had to reinstall it, and everything ran smoothly from there because I just reinstalled the driver which originally came with the laptop.

Now, this is the problem. I tried installing the driver, and the installation seemed to go fine, I was prompted to restart, did so, but when I logged in after the reboot, I was still getting the "No Audio Output Device Is Installed" error. I searched around, tried a different Realtek HD driver. Same result. Tried again with a different driver, no luck. Wax on, wax off.

I can't figure out why it's happening, but maybe someone here can?

For reference, my Laptop's a Sony Vaio VPCCW1S1E, running Windows 7 Home Premium , and I have tried to install the drivers available from Sony for this laptop, but they don't work either :/

Thanks!

First you might want to press the Windows key and the pause/break key. That will open the System screen, once there go to Advanced system settings, upper left. In the window that opens go to the Hardware tab and click the Device Installation Settings button. Select No, let me chose what to do, and Never install driver software from Windows update. This will stop windows from replacing/updating that driver to the one that doesn't work. Then I guess I would go to Programs and Features and uninstall and reinstall your sound drivers. Or go to Device manager and uninstall your sound card, reboot and do the driver install again.

Just did all of that, along with the uninstalling and reinstalling, and still nothing :/

In Device Manager when you right click a device and select uninstall, you should get the option to delete the drivers? Have you tried that? Another option is using system restore to go back to a point before this all happened. You could also try disabling the onboard sound in BIOS, boot into windows once, reboot and enable it again. That might nudge Windows into correctly detecting it again.

Yup, I tried deleting the drivers and then reinstalling them, and the earliest system restore point is yesterday, after the problem started :/

I also tried disabling the onboard sound in BIOS, but there's no option in BIOS to disable sound...

The no BIOS option to turn it off may be because its a laptop and you can't easily add another sound card. You might end up doing a clean install or a recovery to factory state if that laptop has the recovery partition and or recovery disk set. If you have an actual Windows 7 DVD you could try booting from it and doing a repair. Repair Install