I had left my computer running. It went to standby, I didn't turn it back on until the next day. when I tried to adjust the volume by clicking on the icon in the system tray it said there was no device and it was going to close the program, then the icon disappeared. I can still adjust the volume by going to control panel, but the icon won't reappear.

Right click on the system tray and go to customize notifications and you should see a bunch of options appear click the volume and make sure it say always show or hide when inactive then your problem should be solved. Good Luck. Let me know how it turns out.

theres a checkbox in sounds under control panel which says "Place Volume Icon In The Taskbar"

That was it, thanks.

I am experiencing same problem but after I changes to {always show] & rebooted they still do not appear. any suggestions? thanks Dick