HD AV Cable doesn't work: culprit?

Ok so I just got an Xbox 360 (pro bundle) and in a few weeks, the HD AV cables stopped working, the Video(yellow) cable didn't work. I think either the xboxhas a problem or the cable.So who's to blame? Xbox 360 or the cable iself?

there is a swich on the cord for HD and standered def, if its on the worng setting it wont workseventy5cent832

were is the switchBrutalSh00ter