Angerwing said:
Repression is a defence mechanism when the brain can't handle something. I could go way into it, but I won't. It's a psychological term, where what you experienced was "remembering something you haven't thought about in a long time".
You spelled "defense" wrong, just to point out.
Secondly, your last sentence makes little sense, and doesn't actually describe repression. It's been mentioned several times above, that the basic idea is one undergoes something so traumatic that the only way the mind can deal is by locking it away so that your conscious mind can't retrieve it. It's why hypnotism is supposed to be so effective in bringing such memories to the surface.
That being said, repression is an incredibly rare psychological event. So rare, in fact, that many of the people who believe themselves to have repressed memories, do not. They end up surfacing a bad dream or fantasy that they in turn believe is an actual memory. So unreliable is the idea of an actual repressed memory, that when used in a legal setting, it almost never hold up as valid testimony.
I believe I repressed a memory where I molested myself. It was devastating.