When you re-installed Windows, did you also remember to install of the drivers for your computer? The lack of a sound driver, for example, may well explain why you've not got a 'Volume' icon.
If you didn't (and you also failed to back up the drivers before wiping everything), you'll need to go to the website(s) of the manufacturer of your computer and/or of the relevant components (such as your sound card, or motherboard if your computer only has 'on board' sound) in order to locate, download and install the drivers. (Always try the manufacturer's website first, as that may well have all of the drivers you require, saving you having to go to lots of different sites).
Chris