Sound to TV Has Stopped

My computer and TV are linked by both HDMI and audio cables. Everything was working just fine for a long time, until, apparently, a Windows 7 automatic update. Now I get the picture, but no sound. There is no problem getting sound to the computer speakers, the TV works fine by itself, and I have established that there is nothing wrong with any of the TV's inputs. Windows says that everything on the computer end of things is functioning correctly. What could be wrong, and what can I do about it?

Now that I'm at this reply box, I can't see your specs to refer to in gathering mine for you; apparently, I can't copy-and-paste from the Device Manager list; and I can't get the whole thing into a screenshot. I hope the following copied-by-hand excerpts are sufficient.

Sound, Video, and Game Controllers: Intel(R) Display Audio
Realtek High-Definition Audio

Processors (4 identical ones): Intel(R) Core(TM) i3-3220 @ 3.30GHz

Display Adapters: Intel(R) HD Graphics

Network Adapters: Microsoft Teredo Tunneling Adapter
Realtek PCIe GBE Family Controller

The TV is a Panasonic with a 720p display and two HDMI input sockets. The audio didn't come over the HDMI cable, so I ran audio cables from the PC to the TV's audio sockets for the appropriate HDMI input selection. That was working just fine for years. I have tested the TV's input receptacles, and nothing has changed on the TV's end of things. One of the things that I tried, thinking that maybe the Windows update had somehow changed how the computer exports audio, was to disconnect the audio cables. The results did not change.