It is possible that the monitor is not receiving the video signal from the computer. To fix this, you will need to plug in a different monitor and restart your computer. If the monitor still does not work, it might be time to replace it.
If you are using a laptop, try plugging in an external monitor and see if it works. If it does not work, there might be an issue with your laptop’s graphics card or motherboard.
Eventually, restart your computer in safe mode. If the problem still persists while in safemode, this means that this could be a hardware issue.