MacBook display images in sepia only

My sister's MacBook is doing this and she asked me for help,her son was playing with keyboard and somehow after playing theres no way that the MacBook can have images back to regular,all images are in sepia,the kis was only touching the keyboard,he didnt damage anything else,now everything in the computer displays in sepia and i cant find any solution to make it work normal,can anybody please help on this

control option command 8 all pressed together should fix it. If you ment negative not sepia

Hope it helps
Clay

Oh and if it happens again or another "keyboard" mishap. You can always go to system pref/keyboard & mouse/keyboard and look for the symptom your having and the solution