display is not in color

Display doesn't calibrate back to color settings, have checked monitor's chromatic #'s & they make black & white how do I get access to change these back without wiping and re-booting the drive w/ original disks. What do you think happened? None of my imac display settings come back in color although the display does show color when rebooting, then a black and white apple logo appears.

Also need to defrag how do I do that.