I had a bug on my pc and I had to turn it off by power button. When I turn it on again the second screen did not turn on. I tried to restart it, but the problem remains. At startup and closing, screen shows the bios. Also when choose windows to load (I have them installed too) the second screen works perfectly. One week ago I had the same problem and I formated the linux. It worked, but I don't want every week to format them. Have you any idea to propose?
I have a Dell SE2717H and a Flatron L1718S screens with nvidia geforce 1050Ti, and B250M-DD3H motherboard. The dell is connected on gpu(HDMI) and the flatron on motherboard(VGA).
Finally I ran this: sudo ubuntu-drivers autoinstall And it my screen is now repaired. Thanks Everyone. (If you have the same problem see here)