strange tint to screen color that cant be fixed

somehow randomly hit a few buttons on my keyboard and now my screen has an odd blue green tint to it.i have not been able to change this with the normal windows color changing in the properties menu. its nothing to do with the monitor as it changed color right when at least 2 keys were hit together accidentally.i suspect one of them was control but i cannot find any shortcuts in win xp that would do this or remedy this.any ideas on what caused this or a way to fix it?

 

What make and model of monitor? Some monitors respond to special key combos. Dell comes to mind.

 

samsung 940b lcd monitor.looked and can find no shortcuts for this monitor as well.any kind of monitor test i can do? trying to find any right now and nothing comes up