When using versions of Windows Vista or Windows 7 to enable the display of the volume icon in the tray you need to open one section of "control Panel" - it's called "System icons". The easiest way to do it through the control panel. Hover the mouse over the icon to display hidden icons is an arrow at the left edge of the notification area of the taskbar. Click the right mouse button and POPs up the context menu select "Properties".
In the column "System icons" window that opens, locate the word "Volume." Under "Behavior" next to this inscription is placed a dropdown list with two items - select the line "On".
Under the table in the window placed two links for further action. Click on the first of them is "customize notification icons". In this same window, new page will be loaded with the same table. Again find in it the string "Volume". This time the drop-down list in the column "Behavior" will contain three options set to "Show icon and notifications" and click OK. A white icon with a stylized image of a speaker should appear in the tray.
You may need to return a different icon - icon call the Manager, Realtek HD. She looks exactly the same as the icon of the system controller of the sound, but coloured orange and is designed to call the driver of the audiocard with more detailed settings audio. If you haven't used this icon for a while then the OS put it in the list of hidden icons. Click the "Show hidden icons" at the right edge of notification area to open the list, you will find this icon.
You can instruct the system to never hide this icon. Click "Show hidden icons", right-click, select "Properties" and click "customize notification icons". In the column of "Icons" find the words "HD Audio Control Panel" next to the red icon and in the drop-down list, select "Show icon and notifications". To commit the changes, click OK.