There are a few possible reasons why your display may be black and white:
1. The video cable between the computer and the monitor may be loose. Check to make sure the cable is plugged in securely at both ends.
2. The display settings may be set to black and white. To check this, open the Control Panel and go to Display > Appearance > Advanced. Under the "Display" heading, make sure the "Use Windows colors" option is selected.
3. The monitor may be set to display in black and white only. To check this, open the monitor's menu and look for a setting that allows you to change the display mode.
4. The video card may be faulty. If you have another computer or laptop available, try connecting the monitor to that to see if the problem persists. If it does, then the monitor is probably not the issue.