What I mean by “writer’s block” is when someone stares at the paper / screen & can’t think of what happens next. This should never happen.
If you’re ever reduced down to just one interesting thing that could happen next, it means you’ve written your story onto train tracks, and your story is now boring, because only one interesting thing could happen next.
If you’re down to zero interesting things, that means you didn’t stop when you had just one interesting thing. You need to back up at least to the last point where you had to choose between two interesting things that could happen next, because everything after that point is no good.
But even focusing on what happens next is weird. Why are you staring at the last word on your page? What about the setting of scene two–should it move to a different location to symbolize progress from scene one? Is the level of omniscience you gave character A in scene 3 inconsistent with her puzzlement in scene 1? If your story isn’t finished and you don’t still have a dozen different issues to reconsider, something has gone wrong. Either your story is too simple, or you’re an incomparable genius, or you’re not being demanding enough. Stories don’t drip out of the pen in an ordered, final state. It just can’t happen that you’re stuck on the last word you wrote, yet have no questions about anything that came before or will come after it. There should always be problems throughout the story all shouting for your attention. The particular point in the story where you last stopped writing should not be so prominent in your mind.
Why are you writing the story from start to finish? Seriously–why would anybody do that? Do you not know how it’s going to end? That means you’re not writing a story, because you don’t yet have a story idea. A scenario is not a story. If you don’t know which direction to go in because you don’t know where you’re going, I don’t think we should dignify that with the term “writer’s block”, as if it were an aberration rather than exactly what you’d expect to happen.
The normal state of writing is not staring at the last word on the paper and wondering what could happen next, but thinking about the entire story, the entire set of possible stories, characters, and events you considered while writing it, and choosing where to strike next, what to change, and which alternative to use, to hammer the thing into one unified story. The normal state is to have too many possibilities, not too few.
If I have a dozen scenes that need to take place then I should be able to work on them in any order. I could have written scenes 2, 6, and 1, in that order, because those are the longest scenes, (and it’s easier to start with scenes that have some meat to them.) Even then I might have a lot of issues up in the air: How much should Character A know about what’s going on? How much humor do I get from her being oblivious versus being sweetly nefarious? Same question for Character B. Should Character C appear in the scene related to her interests, or should Character B stand in for her? Have I got too many people in scene 1? I have a weak transition marked in the middle of scene 1, around a joke that doesn’t really work. Can I punch it up and make it funnier, or rip it out? Can I substitute a similar joke? Can I delete the entire opening and so not need that transition? Is scene 6 too long — it should be picking up steam as we head into the final scene, not dragging out its joke. Etc.
My point is that even though this hypothetical story is a very short one, I could easily reel off twenty issues in the first 2,000 words demanding my attention. Issues that any story is going to have and any writer should be thinking about. If I were stuck, I’d start working on these 20 issues, and I guarantee that at least one of them would open up a path forward where I was stuck. To get writer’s block, first I’d have to resolve all these issues to my satisfaction, and that never happens.
There are always dozens of issues that could go another way in a story, even when it’s “done”. If you’re staring at the screen and don’t have even one issue demanding your attention, something went badly wrong long before you got to that point.
Most likely, the problem is either
(A) you don’t know how the story ends, or
(B) you’ve eliminated tension by closing off too many possibilities earlier in the story, or
(C) you haven’t got enough awareness of craft, technical issues, and how life works to detect the problems in what you’ve already written, and to focus your attention on what the unwritten sections of the story need to accomplish and to avoid.