Alright, no fun pre-amble, no anecdotes about something tangentially related to being mired in plot tangles only to triumphantly comb them out. If you’re here, you may very well be in crisis. Plot crisis. You’re stuck.
Getting unstuck is never easy, but I’ve found this method makes it a lot less painful.
First, you write down, in less than a sentence, the last plot beat you have that you love. Even if it was three thousand words back, that’s what you write.
Then, skip to the bottom of the page and write the next known plot beat or scene that you love. If you don’t have anything you’re looking forward to writing still, take a minute to close your eyes and imagine a scene with your characters that would be really fun to write. Do you like hurt/comfort scenes? Wild bedroom romps? Terrible monsters? Imagine that scene and then write it as your next beat.
(Left image: Just two scene ideas. Properly social distanced)
Circle or bold those two beats if you're feeling fancy (or want to procrastinate for two more seconds) and then begin the hard work! What might happen immediately after your last point that will lead towards your next point? OR if that’s not working, what could happen just before your end point? They don't have to be good, either! These aren't going to be your final scenes or plot beats, likely. We're brainstorming now and in brainstorming the only wrong answer is to not write anything at all.
Then follow that line of thinking down (or up) until you get stuck again and go back up to the last new plot beat you created that you liked and branch off with a different option.
(Below: Slightly more scene ideas branching off, many of them horrible.)
Really stuck? Start writing out things that definitely will not happen next. Your brain will think this is so pointless it’ll automatically give you something at least slightly better to think about.
Once you've got a good crop of bad apples, take a look at the most likely path and try to connect the top "known scene" to the bottom "known scene" with that path.
If that doesn’t work, try eating an apple or something. Maybe some more leafy greens. Brush your teeth. Drink water. Kill off a minor character.