so sound is working fine but when you right-click on the little white arrow on the right side of the taskbar (the arrow that shows hidden tray icons) and select properties you can't switch your sound icon on?
if so, sounds like a bug to me -> report it to MS.
My sound icon has disappeared as well now, sounds all working fine I can open sound control in control panel and adjust but it's frustrating.
As has been mentioned showing hidden icons have "Volume speakers 2%" and it is set at showing icon and notifications, if I change this then back it quotes that it will be show when next activated?????.
I've been in control panel sounds and tried to find something that turns on the icon but can't find anything.
Has anyone sussed this out please?