Can You Hear Me?

Sigh. The latest Windows update seems to have borked my audio. System sounds work, but WMP and YouTube both are silent. Settings asserts that my NVIDIA HDMI Output is "Not plugged in". I've checked on line, but the suggestions either don't work or can't be carried out. The old standby, "When in doubt, reboot", has been of no use either. Anybody know anything?