Neurophilosophy has a fascinating post on amnesia in the movies, and how it relates to different kinds of amnesia in real life. Accurate portrayal? Think Finding Nemo, not Fifty First Dates.
I have experienced amnesia of an event due to a head injury. Since then I’ve learned a lot about memory, and what a plastic thing it is. But I never got any memory of the accident back. I guess the tape was off the capstans and that’s that.