Come back means to return somewhere, and can also mean to "make a comeback." If your boyfriend or girlfriend became angry and left you, in a converation you might beg them to come back to you. If an athlete had a good start to his career and was injured, he could try to make a comeback from the injury and play again. Get back can also mean to return somewhere. "If you hike in the forest, always make sure you know how to get back." To get back can also seek revenge on someone. If they make you upset, you can plan to get back at them. Go back just means to return somewhere. "Why are you staying here? Go back to your family!"