Having Sony Vaio VGN-NS31S with Microsoft Windowns 7 Ultimate 32 Bit OS ones already have all the latest drivers installed including update for Windows 7 but the Fn Keys drivers for VGN-NS31S seems couldn’t find
To resolve this issues, the direction you can aim to find any drivers for Sony Vaio VGN-NS31S, just go over sony Vaio support site here.
There you can use the latest stuff of Windows 7 tab. The originally installed tab will also have some files that you need. Just find which the right drivers for your laptop.
Another solution you can do is CHECK first, do you have Vista which originally installed on your VGN-NS31S laptop. Some people who’s experience similar problem didn’t do this. So, if it was then simply use Vaio Event Service. After following their suggest, you should now see all of Fn keys are working properly