Missing Volume Control Icon

Please follow the below steps:

1) Click on Start button,
2) Select Control Panel,
3) Select Sound and Audio Devices,
4) Place a check mark at the check box (small square box) for Place Volume in Task bar.

If you do not have Windows XP, you can try to reinstall your sound icon by going to Control Panel -> Add / Remove Programs, Windows Setup tab and then double click the Multimedia icon and place a checkmark on Volume Control. If it is already there, take the checkmark off, then click OK. Then go back in again and place the check mark on.

It is also possible there is a problem with your sound card. Device Manager (Start -> Settings -> Control Panel -> System) may pick up a conflict, or the sound card just bit the dust and may need to be replaced.

Also please visit:

Article Title: How To Display the Volume Icon in the Notification Area in Windows
http://support.microsoft.com/kb/279435

Article Title: To display the volume control icon in the notification area
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/soundscpl_volume_control_on_taskbar.mspx?mfr=true

http://www.computerhope.com/issues/ch000208.htm