Since there are several different post about this issue it would be for me to post to them all with a fix. So I will make one post here.
1. Left click on windows icon and choose settings.
2. Click on display tab.
3. Change the size of text to 125% Then apply.
4. DO NOT LOG OUT YET. Choose sign out later!
5. Change the text size back to 100% and click apply.
6. Now sign out and sign back in.
Your volume icon will be back. =)