All defenses do this to some extent. You have no conscious memory or knowledge of that which is repressed. Suppression is when you consciously forget something, or make the choice to avoid thinking about it. The problem with repression is that the memory, feeling, or insight repressed doesn't go away. It continues to effect us because our unconscious gives it a life of its own.
Withdrawal takes several forms, such as silence, running away, and drinking and drug use.
Talking to friends could prompt them to ask about painful events, so you avoid them. Paired with fantasy, it can be paralyzing. Withdrawal inevitably leads to strong feelings of loneliness and alienation, however, which generally means you feel more pain. This is one of the most difficult defenses for some people to understand. That way, we aren't threatened by the feeling, or even the awareness of the feeling.