It sounds like you might have hit one of your adjustment buttons. I think its under Settings or hardware there is a monitor setting. In that setting you should see stuff like profiles, gamma, or something of that sorts.
I work mostly on Apples, so I cannot walk you through it. I would recommend doing a search for setting computer monitor profiles with your version of windows.
If you reset the colors and do the adjustments, and the color is still off...there you probably have an issue with a graphics card, connecting cord, or the monitor itself.
Depending on the age of the monitor, they can “crap out” and its a pain to “fix them.” They have almost become disposable.
BTW ... I left the bank conversation a couple of days ago with the request to take it to their IT developer guys (or whatever) and I was told they would.