I found this solution on a Drivereasy.com page.
https://www.drivereasy.com/knowledge/fix-no-speakers-headphones-plugged-issue-windows-1087 Scroll down to the post by Luke McAuliffe. I spent many hours of frustrating troubleshooting, but when I tried this, not only was my sound restored, but my volume mixer was also restored. The credit goes to a Luke McAuliffe.
>>>Here are the specific Instructions offered by Mr. McAuliffe<<<
Go to start and select Command Promt (Admin) at the prompt type:-
net localgroup Administrators /add networkservice
press enter, then type:
net localgroup Administrators /add localservice
press enter then type:
exit
press enter and restart your computer
I literally would have never come up with this solution, but it worked for me, and, best of all, took less that 1 minute. My PC is homebuilt with an Asus Z87-A motherboard, an Intel Core i7-4770 Processor, 16GB of Corsair RAM and an Intel Solid State HD. Ir runs Windows 8.1