A many times a silly something that could annoy a user while using Windows 7/8.x is missing tray icon(s) for volume control,
network connection (rarely), which allow the users to toggle the volume on off and here is the quick fix to bring those tray icons back without restarting the computer
Start Task manager (CTRL+SHIFT+ESC altogether)
Scroll down and locate “Windows Explorer” , right click the process and restart!
Once the process restarted, you MUST able to see the tray icons relaunched.
Cheers guys & enjoy