OK I tried that, and it didn't work. Any other ideas?
If you're up to it, check that the display card is seated properly. Also
check that the cable from the monitor to the display adapter is securely
connected and not pinched anywhere. If the monitor has on screen color
adjustment buttons, try those. If color adjustment is available in Display>
Settings> Advanced, try that as well.
If everything is still green and if it is possible, try a different monitor
to see if it has the same trouble or not. If both monitors are green,
suspect the display card as faulty. If only one monitor is green, it may
have lost a color "gun." Usually cheaper to replace than to repair.
(Monitors create images using red, green and blue. When one of the color
guns stops working, there will be an absence of one color and overabundance
of another.)