Assuming you've give it a while to perform all of its' post upgrade machinations and you still have no sound, then....
I would look first to playback devices (right click the speaker and choose playback devices from the context menu) confirm that it is using "Speakers" as default (Green check mark) and that those "Speakers" are associated with the proper audio device default.
If that seems correct then select it and then click the "Properties" button, select the advanced tab and try experimenting with a different format from the drop down. and test.
IF that doesn't seem to prove particularly helpful, then open device manager, expand Sound, video and game controllers and right click the problem device and select uninstall.
Reboot and let the native, found new hardware wizard re-install it.