Fifty First Dates is one of my all time favorite Adam Sandler movies. In this movie, the main actress (Drew Barrymore), was involved in a bad car accident where she isn't able to make new long term memories. Adam Sandler falls in love with her and works every day to try to get her to fall in love with him, but it's a challenge since each morning she wakes up and has no idea who he is. He work on it by making videos for her and constantly visiting her hoping she'll start to remember.
This may not be the most accurate portrayal of how memory loss happens. I'm sure it depends on the nature of the accident. In this case, Drew Barrymore remembers everything up to the crash, but nothing after the fact. I think if we were to look at how it happens naturally (with diseases such as Alzheimers), we would see that it is a much more gradual experience, and people start to forget more and more things as time goes on. One aspect from the movie that doesn't seem to make much sense is the regularity of when she forgets everything. In the movie, she forgets everything as she sleeps, so you can predict whether or not she's going to remember you. In real life, it's much more complicated than that, and people forget things over longer and shorter periods of time (partially depending on how important the matter was to the individual).
This is just a simple illustration of how Drew Barrymore felt in the movie when she woke up with a strange man (Adam Sandler) in her bed in the morning. Obviously her reaction was a bit more dramatic as the circumstances were a slightly different