My volume icon missing in system tray. wat to do?

Sometimes Due to virus infection,they corrupt our volume icon in system tray.
and when we go to control panel to see the volume setting.we find all the features are disabled,means our volume is gone

even in this case ,when we try to play a music file ,we hear nothing but a pindrop silence,while our songs is still played
To over come this ,i have a simplest solution

open a notepad and copy the following:

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
"NoSaveSettings"=dword:00000000
[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run]
"SystemTray"="SysTray.Exe"


save it as volume.reg.
just double click the file and say "yes" ,"ok"
Then you can see your volume icon appearing in system tray.If not just reboot