I brought my 360 over to my brother's place for some Halo4, but he has an older HDTV that we didn't realize doesn't display progressive (only 1080i, not 1080p). My settings were set to 1080p, so we couldn't see or hear anything and I only had my HDMI cable with me.
Through a combination of youtube and my memory, we were able to change the settings just by calculating the button inputs on the controller
RB x 6 A x 4 Up A
It took us a while to get it right (thought the second step was A x 3 until we remembered Display Settings, thanks youtube), but felt so satisfying once we were able to play.
Has this ever happened to you? If it does, now you know the button inputs. Just remember, it asks if you want to confirm the changes once you're done, and you have to hit A again to accept - if you wait more than a few seconds (and it takes a few seconds for the screen to show up) the settings revert and the signal is lost.
Sorry, this is a gaming message board. We don't play games, we just complain about them.