Go back <-- go to where you came from previously. "Go back home" Come back <--- it means the person left and you want them to return. "Come back to my house" I hope this helps you.

A son leaves home to go to college. Later, the parents begin to miss him. They say "I wish he would come back". The son is now at college and he wants to go home. He says "I want to go back". It is just a matter of who is staying and who is moving towards. The parents are where he was originally, so they want him to return or "come back" to where they are (they stay). The son wants to leave where he is and return or "go back".