Instructions
Open your television's "Picture" menu and check that the "Color" is set to 10 percent or higher.
Disconnect the console from any intermediary devices such as VCRs or switcher boxes and connect the Wii directly to the audio/video ports of your television itself. Turn the system on and tune to your television's A/V or video channel. If the picture now displays in color, the problem is not with your Wii but with the device it is running through.
Disconnect the Wii's A/V cable from the back of the console and from your television. Blow gently into the plugs on either end to ensure no dust or particles are obstructing the connection, and then reconnect the cable by firmly pushing the plugs back into place.
Reset your Wii and load the game you are trying to play while holding "B." Change "Scan Mode" to "Interleave," and then select "OK" to load the game in a mode that is more likely to be compatible with your television.
Turn on your Wii and select the "Wii" icon in the lower-left corner. Choose "Screen" and scroll down to "TV Resolution." Highlight "Standard TV" and choose "Confirm." If your Wii is set to a resolution too high for your television, the set may display the picture in black and white only.
Contact Nintendo if the preceding steps do not fix your problem. If fixing connection and software issues does not work, the fault may lie with a hardware problem in your Wii.