Somehow a button was hit on the cable remote and we have sound with the cable channel banner but no picture. We checked the TV with a USB and a photo appears so it's not the set which is new. Unplugged everything to no avail. Any ideas as to what might cause this?
does the remote have a wide or HD button?
go into the tv's settings and reset it, see if there is some sort of HD resolution setting. Change it to auto.