I have a hunch that your L310 left the factory with either Windows Vista or Windows 7 pre-installed, since only Vista & Win-7 drivers are available for it from the Toshiba Asia website. So either you or a previous owner probably downgraded it to Windows XP.
You are probably trying to install the Windows Vista or Win-7 audio driver. Vista/Win-7 drivers will not work on XP.
All I can suggest is that you revert to using Windows Vista or windows 7 on your L310, or use Windows XP on it without sound.
However, if you look in Device Manager, you'll probably find other drivers are missing too, so reverting to the original OS is the only sensible option.