Why Is My iPhone Screen Black And White?
There are two areas to check for disabling a black and white (grayscale) screen on your iOS device. First open the Settings app and go to General > Accessibility. Make sure Grayscale is toggled to the Off position.
Alternatively, the Grayscale Zoom Filter might be enabled on your device. To check, double-tap on the screen using three fingers. That should exit zoom mode and return the color to your screen. You can disable the Grayscale Zoom Filter by going to Settings > General > Accessibility > Zoom > Zoom Filter and then select None.