The computer you have comes with switchable graphics and it uses a special configuration. From our side, I can provide the graphics driver for your controller and it can be downloaded at the following link:
In the case that the issue persists, I recommend you contacting the computer manufacturer so they can guide you with the configuration while using two graphics controllers.
Thanks for your answer. However, as I said before I uninstalled and reinstalled current drivers numerous times for both graphic cards. There is no problem for my laptop, since I can obtain display from other monitors.
My monitor works if I connect to a computer using UBUNTU. But there is no display with other computers using Windows. It is obvious that a firmware like a driver caused this problem. But there is no rational reason for this issue. I hadn't changed anything or download any update before this problem arise.
I dont understand why external monitor started not to work with computers using WINDOWS. I tried ten computers using Windows, though there is no display.
At this point since you have tried the drivers, I recommend you installing the monitor drivers and if possible disable the external graphics at the bios level. By doing this we can discard any possible compatibility issue on your unit. Another good step is to test different HDMI cables or change to a different monitor.