have nothing to say for (oneself)
1. To be unable to defend or explain one's behavior. I confronted Tommy about breaking the vase, and he had nothing to say for himself.
2. To struggle in conversing with others. That guy is a real dullard—he has nothing to say for himself.
have something/anything to say for (oneself)
1. To be able to explain or defend one's actions. I told you not to throw the ball in the house, and now, the vase is broken. Do you have anything to say for yourself?
2. To be able to converse with others. That guy is a real dullard—he doesn't have anything to say for himself.