It is possible not to think about something for a long time, even something unpleasant that happened to you. But what's been claimed in these repressed-memory cases is something, by definition, that's too extreme to be explained by ordinary forgetting and remembering. They're saying that in order to go on in life, you had to wall off this memory, because it would be too painful to live with. Then finally you go into therapy and crack through the repression barrier and out comes this pristine memory. But there really is no credible scientific support for that notion.