I'm in the middle of NaNo like so many other writers this month, and I'm completely stuck. The first 30K went really smoothly, but I reached a point where I just can't seem to get my characters to move toward the next major plot point.
To further complicate matters, I had another truly compelling idea for a book last week, and it's clamouring at my brain for attention.
A part of me wants to stop writing the book I started at the beginning of November and work on my new shiny idea, but another part of me tells me to finish what I started.
To be honest, I think you could do either. There's absolutely nothing wrong with dropping the project you started and picking up another one if the other one is really banging at your head to get out. Just add your word count on the new novel to what you already have on the one you've started, and you can still win NaNo.
I've done that before. More than once, in fact. You don't end up with a finished draft by the end of November, but you're still a lot further into both books than you were at the start.
But if you feel like you need to finish the book you started in November, you should do that. Just ignore the place you're stuck and move on. Leave a note for yourself or a big swathe of blank space so you remember there's stuff that needs filling in and move on to the next point in the story you're excited to write. Often once you've written the stuff that comes after the place you're stuck, you find a way to move through it.
That's one of the reasons I rarely start writing a book at the beginning. I almost always start with one scene that really demands to be written, one event which is the core of the story I'm trying to write. So I write that and figure out from there where the story goes next, or how it got to that point. Usually both..
The most important thing to do is keep writing. You've made it through 19 days of this madness, so don't give up now.