Since I installed Windows 10 on my Toshiba P-70A laptop, the computer does not recognize the second monitor.
To make the second monitor work, I had to uninstall the display drivers and remove them from the computer:
- Open the File Explorer
- Right click This PC and select Properties
- In the upper left corner select Device Manager
- Expand the Display adapters section
- Right click each display adapter,
- Select Uninstall
- Check Delete the driver software for this device
- The computer will reboot.
To keep your second monitor working do not update the display drivers, keep the drivers that Windows installs during the reboot.