When writing a full novel, you are going to need to rewrite the dang book multiple times. Sometimes you will completely change ideas and other times you ill completely screw your book up and need to go back to an older version to recover your story and try again. Once, I completely lost two whole chapters and I had to go back to an older version of the story to recover them.

NEVER THROW AWAY YOUR OLD STORIES!!!

You will regret it is you do.