HDMI stopped working but Xbox is on

How do I turn on and off display discovery

I have the same problem. Iv tried countless tactics but nothing is working. i have sound but no picture. I even went as far as buying an HDMI/DMI adapter. Still nothing. Did you ever get yours working?

No already tried both above. Reset graphics only applies to AV settings as hdmi should auto detect but doesn't. Can't change HDMI settings using AV cable as grayed out. Only suggestion that seems likely to work was use a different telly and then switch back.
This means dismantling the media centre and taking a fair distance then reassembling. Would have thought Xbox would have a hard factory reset or something, worked fine on original settings.?

Hello ScenicMicrobe12,

Please try the following:

1. Remove any discs from the disc tray.
2. Turn off the console.
3. Turn on the console.
   
   Note: If you are using an Xbox 360 Wireless Controller, turn on the console by using the Guide button on the controller. Make sure that you use the player 1 controller when you do this. The player 1 controller will have the upper-left light illuminated.
   
   
   
4. As the console starts, on the controller, press and hold Y while pulling the right trigger. The display settings are reset to the default settings, and then the console automatically restarts.
   

See if that works out for you.

Did the right trigger + (Y) thing again and my wifi is back but still no signal with the HD lead

I guess I should be a 'glass half full' kinda kid . . . .