Are you trying to extend, mirror or duplicate the display?
How are the monitors connected?
What cables are used to connect the monitors?
Have you tried checking with different video cables?
As you mentioned your laptop has stopped detecting the second monitor.
Use the following instructions to either extend or duplicate the desktop with a second monitor:
1.Right-click anywhere on the desktop.
2.Click Display Settings.
If only one monitor is showing in the window, first verify that the connections are secure between the monitors and the computer. Then, click Detect. If Windows does not recognize both monitors, click Identify. The numbers 1 2, or 3 are shown on the monitor icons to help you identify the monitors.
If Display, Resolution, Orientation, or Multiple displays selections in the Screen Resolution window are dimmed, not allowing you to make the desired changes, see; Configuring the display with the display driver.
3.Use the Multiple displays drop-down list to select one of the following options:
• Duplicate these displays: Show the entire desktop on both displays.
• Extend these displays: Stretch the desktop across the two displays.
• Show desktop only on 1: Use only display 1 and show nothing on display 2.
• Show desktop only on 2: Use only display 2 and show nothing on display 1.
4.(Optional) To change the direction of the desktop extension (usually left or right to match how the displays are physically positioned), select a monitor and drag it to the desired position.
5.When done, click Apply.
Refer this article to know more information about using two or more monitors.
Hope this helps! Keep me posted.
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