I’m sure you’ve seen it before, be it in writing, television, movies, or even in video games. Lost memories is a very common, if not overused plot device. It’s easy to work with, and it can bring in a lot more in the future. NEVER USE IT.
Let me explain. To make a good story, you have to do things in a way that people haven’t seen. You have to make something that engages someone. Amnesia has been used too many times for that to be possible. You have the Bourne series, X-Men, Arc The Lad, Kyle XY, Metal Gear Acid, Bioshock, Eternal Sunshine of the Spotless Mind, and many other examples where amnesia is a huge factor in the story. Now, I’ve used it before in one of my stories, but to pull it off, you literally have to make it something that doesn’t play into the entire story. It can be a reason for something, but if you want to be taken seriously, then I don’t suggest amnesia. It’s just way too overdone. You can use many other elements to explain or move a story along.