Central character emigrated to Zanzibar?
Most exciting plot point collapsed into 'Who wins the Knitting Competition?'
Kitchen floor been washed so much you can see the joists through the threadbare lino?
Here are ten ways to come un-stuck when you've come unstuck:
Abandon the middle and go to the end.
Write the last scene. And then the second-to-last. And so on. In other words, go backwards for a bit. If you're lucky you'll bump into yourself writing forwards and bingo! Finished screenplay!
Stuck for some plot?
Try re-telling your story from the point-of-view of a couple of the secondary characters. What happens when they're the central character? This usually generates new plot.
Stuck on your Character Arc?
In two columns describe what your character LOOKS LIKE at the beginning of the story and, in the second column, by the end. How has their hair-style changed? How do they dress by the end of the film? Visual changes will give you clues to their emotional change. If they look identical you've got a problem - put them in totally different clothes and ask, 'What would have had to have happened for them to change their look to this?'.
Buy some post-its.
Throw out your index cards and buy some post-its. Using different colours, summarise the plot, goal and character arc in short story beats then stick them up on your wall. Your entire screenplay structure will be on display and the faults will be easier to spot. If you suffer from insomnia because you wake, every night, with a brilliant idea for a brand-new screenplay, which is ten times better than the one you're working on at the moment, stick the post-its on your bedroom wall; when your brain sees how much work it is to complete a screenplay it will go straight back to sleep and never wake you in the middle of the night again.
Buy an expensive notebook.
Half way through Act Two you can become disheartened if you feel your writing's getting sloppy. So get sloppy on the computer, but in your brand-new, leather-bound, cost-a-packet notebook, re-craft those sloppy scenes in your best handwriting (enhanced by the brand-new, cost-a-packet fountain pen you just bought for the purpose). Make sure these scenes are the High Art you know you're capable of - to be typed back into your computer when you need some serious displacement activity The computer equals THE VOMIT DRAFT; the brand-new notebook equals RETAIL THERAPY.
Do different writing tasks at different times of the day.
If you find you're rewriting the first 30pp endlessly rather than getting on with Act Two try allocating jobs to different times of the day. Over your lunch-break you're allowed to fiddle with Act One to your heart's content; after supper you've got to fill blank pages.
Write in half-hour chunks.
If you've got a day job, it's hard to find time to write. Instead of saying to yourself, 'I'll write for four hours every evening when I get home from work', or 'I'll take an exotic holiday in the Caribbean and write for eight hours every day while I'm there', say, 'I'll write for half-an-hour when I get up and half-an-hour when the kids are in bed'. That's an hour - and if you're writing a page an hour in three months you've written a draft of a screenplay.
Write in ten-page chunks.
Sometimes when you're on page 30, page 120 can seem like the other side of the universe. So instead of promising yourself an exotic holiday in the Carribean when you've finished your script, promise yourself a luxury gift every time you get to the end of a ten-page chunk. The benefit of doing this? Twelve holidays instead of just one . . .
Keep to a rigorous timetable.
Always, always write at the same time every day - because even if you don't want to write, your brain will kick into gear. This is because Brains are creatures of habit, whereas Human Beings are lazy slobs who'd far rather be surfing YouTube.
Write something! Anything!
If you're stuck, write shopping-lists, write your Oscar-winning speech, but write something, anything. Maths is good: working out how much you spend on breakfast muffins every month soon bores you enough to get you back to work.