There are a variety of possible reasons why your computer screen may not be displaying properly.
The most common cause is a loose or faulty connection, either between the computer and the monitor, or between the monitor and a power source. Check to make sure all cables and connections are secure and that the power source is connected securely and turned on. Be sure to check both ends of each cable for any possible damage, such as frayed wires or broken connectors. If everything appears to be connected correctly, try rebooting the computer and see if that resolves the issue.
Another potential cause could be related to the video card. Open up your computer and examine the video card to make sure it’s securely seated in the slot. Many cards may require additional power from the power supply to function properly. Make sure the power supply is putting out enough power to support the card, and that all of the connections are securely attached.
If the video card seems to be functioning properly, the issue could be related to the software configuration. Try connecting another monitor to the system and verify that the display is working properly. If it is, then the issue may be related to the computer’s settings. Try accessing the BIOS setup, and check the settings for the video output. Make sure the correct settings are enabled (such as the resolution, color depth, refresh rate, etc.). Additionally, check the operating system settings and make sure it is configured to use the correct video driver.
If all of the above steps fail to resolve the problem, then it’s possible that the monitor itself is faulty. To test this, try connecting a different monitor to the system and see if it works properly. If it does, then you can be fairly certain that the issue is with the monitor itself. You may need to replace the monitor in order to fix the problem.