my sound icon on my task bar has disappered and in device manager it disappeared, however in add/remove programs its there. i have uninstalled it and reinstalled it I even checked bios to make sure my sound was enabled. it used to work just fine im stumped :S
Are you using XP? That's my experience with Realtek as well. In Vista, no problem.
However I would go to your mobo manufacturer's website and make sure you have the latest sound driver. The last version I installed for my mobo does a much better job of sticking around in the taskbar , although it's still not perfect.