Obviously you have yet to read the manual, or even fiddle with it? Go to Shooting Menu - Set Picture Control - Monochrome. Walah... that's B&W.
i read and followed the manual.
but there's no such function.
is there something wrong with the camera?
Perhaps you can't be in any scene modes to access the monochrome menu.
This is why I dislike scene modes in my camera.
I think it is better to acquire in colour and convert to BW. Once u acquire it in BW, it impossible to convert to colour.
for your info, if you shoot raw ViewNX could bring the color back...