You don't ask a plumber, "How do you deal with days where you have a stubborn clog? What's the plumber's block all about?" and I think this applies to writers as well. We all have days where the words just don't seem to want to work for us, but we can't resign ourselves to the cute condition of so called "writer's block." You are going to struggle to get your characters to say and do what you want them to. The best thing I have found is just to write something. Maybe it's a scene that's not going to be in the book, maybe it's a scene later down the road, and maybe it's something completely different like some free verse poetry. The point is, you are writing and your brain is working creatively in some regard, and that's going to be good for the process either way.