Re: how to unmute sound in windows 10
If there is no speaker icon at notification (if there is - remove the cross sign by clicking it) go for long way:
Click start
Enter text from keyboard "Adjust system volume"
Click Best match - Adjust system volume/Control panel (with grey speaker icon before the text)
Remove red disabled/muted marks from under volume bars by clicking speaker icons
If there are no such marks you should have sound. Laptops has some keyboard shortcut to mute/unmute sounds. Check manual.