If your computer monitor isn't working properly, there are a few steps you can take to troubleshoot the issue. First, try connecting the monitor with a different video cable. If that doesn't work, replace the monitor's power cable. If the monitor still doesn't turn on, you may need to replace or repair it.
To identify what part of the remaining hardware is causing the computer not to turn on completely, you can use a self-test ignition card. If you have a graphics card, make sure your monitor is connected to it, not to the HDMI port on the motherboard. If you have additional cables lying around, try another one - maybe the cable you've been using is damaged or one of the ports isn't working properly. You can also try a different type of cable, such as an HDMI cable instead of a DisplayPort cable to see if that resolves the problem.
If nothing happens after you turn your PC on and off a couple of times, that could indicate hardware problems. Similarly, if your screen has been deactivated or confused after disconnecting it from an external monitor, try holding down the function key and pressing any button that looks like a computer screen on the top of the keyboard. If the computer is active but the monitor is still at rest, you can force it to be activated by pressing the Win+P or Ctrl+Alt+Del key combination. Before connecting multiple monitors, make sure that your laptop or computer is capable of running two or more screens at once.
The machines may not support all of the monitors you want to connect. For example, if you're trying to connect a VGA computer to a DVI monitor, you'll need a different type of active converter. Additionally, if your monitor is stuck in an input with nothing connected, you may need to connect something to that port before you can change the inputs to the correct one. If your PC still doesn't display information on the monitor with nothing more than the basic hardware installed, it could be a faulty RAM, a CPU that overheats, or a video card that isn't positioned correctly.
If you're trying to connect a second monitor, either to a laptop or desktop computer, you might have problems where only one of the screens works properly. If you built, upgraded, or moved your desktop computer recently, it's possible that a piece of hardware has come loose inside the case and is preventing the computer from starting up.If your computer does display information on the monitor but still doesn't boot up completely, check for any loose connections inside your PC case and make sure all components are properly seated in their slots. Additionally, if the integrated video card has been deactivated and a VGA cable is connected to it, nothing will appear on the monitor even if the computer is turned on. It is quite possible that the PC will not turn on at all if this switch does not work properly.To sum up, if your computer monitor isn't working properly there are several steps you can take to troubleshoot and fix it.
Try connecting different cables and adapters and check for any loose connections inside your PC case. Additionally, make sure your laptop or desktop computer is capable of running two or more screens at once before connecting multiple monitors.