“I don’t really believe in writer’s block, but I absolutely believe in getting stuck. The difference is one is imposed on you by the gods, and one is your own damn fault.”
~ Neil Gaiman
I believe you can be in a creative rut. But a creative rut half-way through a script is not a rut; it's poor planning.
If you write a strong outline, your writers block should come during the preparation process, not after you Fade In. A strong outline means you've already figured everything out: you know who everyone is, what their problems are, what they need, and where you need to go. It's the Thomas Guide of script writing (sorry- dating myself.) It's the Google Maps of script writing.
How do you write an outline for a screenplay? You can read good books like Screenplay, Story, and Save the Cat, to name a few. You can also take my Screenwriting 101 class, or sign up for private coaching. We all have slightly different ways of outlining screenplays, but they all work.
No matter how you learn to outline, just do it. Because if you end up with writer's block half-way through your script, you're not just screwed, you're also at fault.