If you mean from the task area then you can get it back.
 
Control panel then Sounds, Speech, and Audio Devices then Sounds and Audio Devices
 
Place a checkmark in the box that says Place volume control in taskbar.

If this is related to a post made recently, you indicated that your sound system used Nvidia sound drivers. You can do as amrican zombie says. You can also right click on My Computer choose Properties, then click on the Hardware tab and click on the button for Drivers. Here you can see what kind of hardware you have installed. You will want to make a note of it. In each are that you click (or right click and choose properties) into, you will see a tab with drivers. You can update the drivers there. For the most part these will be Microsoft drivers that will get your hardware to interface properly, but you won't get the bells, whistles, and nifty extras that come with the specific software from the folks at Nvidia or Creative or whoever made your sound card. These would include programs like testing and volume control , etc. For that, once you know what card you have you will need to go to their webpages and download their updates.