Windows 10: Desktop suddenly fails to recognize second monitor

When I start my computer, the BIOS message appears on one monitor in my dual monitor set up.
But when the computer login message appears on my windows operating system, it appears only
on the other monitor, and the desktop does not spread to both monitors.
Rebooting used to solve this problem last week, but now even that fails.
Please help.

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-Log Details-
Scan Date: 1/23/21
Scan Time: 12:09 PM
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SECOND MONITOR NOT RECOGNIZED

i HAVE WINDOWS 10 AND A TOSHIBA LAPTOP.

ALTHOUGH FOR YEARS MY TOSHIBA RECOGNIZED MY SECOND HP PORTABLE MONITOR, SUDDENLY WHEN I GO TO SETTINGS, DISPLAY I DO NOT SEE THE SECOND PLUG IN MONITOR I USED FOR YEARS.

 

windows not recognizing second monitor

Hello,

Windows may not recognize another external display device if the display drivers are outdated, or that the monitor is turned off or not plugged in correctly, etc. For us to isolate the issue in connecting a second monitor in Windows 10, kindly respond to
the questions below:

• Have you made any significant changes to your device prior to the issue?
• Did the second monitor work before?
• Have you tried using the monitor to a different computer?
• What happens if you disconnect your primary monitor and connect the second monitor to make it the main monitor?

We look forward to your response.

 

Windows 10 Won't Recognize Second Monitor Via HDMI

Hello,

I would suggest you to refer to the suggestions provided by
“Karthik Vengaloor” replied on May 19, 2013 in the Microsoft Community link and check if that helps.

windows 8 will not recognize my second monitor

Note: The above steps holds good for Windows 10 as well.

I hope this information is helpful.