Tips and Tweaks - Never Assume the Obvious when Troubleshooting
This tip is as much a friendly reminder as one that even the best technical people will forget--Don't Assume the obvious has been done!
Case in point, I was troubleshooting a friend's TV setup. She has AT&T U-Verse TV which is connected via HDMI passthrough to her Onkyo stereo receiver and claimed that her dog sat on her remotes and then suddenly lost all audio. I looked through all the settings on the receiver and it looked OK. Swapped inputs on the AVR and tested her Blu-ray player, and that worked correct with audio. I then went into AT&T's setup and tried messing with the audio settings. After adjusting some cables and moving things around, I was ready to GIVE UP!
Then it hit me and I asked her, "Have you power cycled your cable box?" Of course the answer was "NO," and of course, that RESOLVED the issue. In my effort of trying to think about all the complicated ways she could have lost audio I missed the most basic troubleshooting step to simply reboot the device.
So there you have it, never assume that the most basic steps of troubleshooting will not fix the problem.