There is always a point in writing a novel or script, when, just like Dante, you are lost in a dark, tangled wood (hopefully it isn't the bottom circle of the Inferno, but sometimes it sure feels like it.) You have no idea what your book is about anymore, or you've lost the character arc, or you just feel caught in the mire and you are seriously, and you mean it this time, seriously thinking of giving up writing and going to air conditioner repair school. Despite this trauma, you can't move forward. Or back. Or anywhere. Sigh. I know the feeling.
There are a lot of story gurus. I took Robert McKee's famed story structure class in Manhattan and left feeling much more befuddled than when I came in (but I did get to see Casablanca again, which was sort of nice.) I had some of the Truby story structure tapes at one time and was enthralled, and by the way, I think everyone should visit his website because he picks apart films and shows you where they work, how and why--and how they don't.
Most of these story structure people are really for screenplays. I tend to show my work to other writers whom I trust more than life itself, but when I was so confused in my novel that I had no idea what my main idea was anymore, I also asked Jeff Lyons, a smart, funny screenwriter, who seems to have this uncanny ability to thrash through the strangling vines and find the story breathing underneath, for help. (Okay, I begged.) Jeff's got this company with the megacool name of Storygeeks.com, and though it's primarily for screenwriters, I swear he knows novels.
Again, I know, I know, novels are not screenplays, but sometimes a little structure can be a very big thing.