Okay.  Been a while.  Here's some advice for you newbe screenwriters, just don't. Go back to bartending, uber driving, or living in mom and dads basement.  

Anyway, stuck story? Get it unstuck.

• If it's the second act and you're having issues with your story getting stuck, check the first act the problem usually lies there.  Did you set up your story properly so it has a narrative drive?
• Did you have an outline, a roadmap, a frickin clue as to where you were going? What's your ending? Why does your story end that way, and why is it important?
• Obsticles and conflict. Are you making your protagonist suffer?  Are you putting them through hell? Are you making it hard on them?
• Do you know your characters?  Do you understand them and their motivation?  Are they acting in accordance to that motivation?  Is there logic to their actions?  Even illogical choices we as readers can understand them as part of the character's DNA.
• Change the POV.  Take a moment and try to write that scene from a different character's perspective (Point of View).  Do you see the scene differently?  Does switching up the POV open up the story?
• Structure Change.  You don't have to be linear always.  You can include a flashback or start off with a flash forward.  You can sprinkle these in if it helps move the story forward and unstuck your stuck story.
• A Twist.  Did you take your story down one path and not ever switch it up, come up with a plot twist that sends the story in an unexpected direction.

There hope that helps. If not, just give up and make it easier on yourself.  

Seriously.

Peace. Out.