Sirs: I have a new Sanyo 42" TV. We are on
If picture and sound is ok, and there is no colour, your push have sometimes made its system changed. I don't know from where you are, and to which country you belongs. Anyway I'll give you one solution.
Your Sanyo Tv may have multisystem compactable. There are mainly three systems in transmision of TV signals, called PAL [Phase Alternating Line], SECAM [Sequential colour and mamory] and NTSC [National Telivision System Committee]. Most of the europian countries have transmitters with SECAM and NTSC. I belongs to India, and here we have PAL BG system.
If the system has changed in the tv, the picture will not have chroma information, ie ,colour information, and black and white picture will be the result. You just do one thing. Just get into the Menu of your TV, according to its documantaion that you have, and go to the system menu, and make it "AUTO". This will solve your problem. Ok.