Handwrite. (If you already are, write in a different coloured pen.)
Write outside or at a different location.
Read.
Look up some writing prompts.
Take a break. Do something different. Comeback to it later.
Write something else. (A different WIP, a poem, a quick short story, etc.)
Find inspiring writing music playlists on YouTube. (Themed music, POV playlists, ambient music, etc.)
Do some character or story prompts/questions to get a better idea of who or what you’re writing.
Word sprints. Set a timer and write as much as you can. Not a lot of time to overthink things.
Set your own goals and deadlines.
Write another scene from your WIP. (You don’t have to write in order.) Write a scene you want to write, or the ending. (You can change it or scrap it if it doesn’t fit into your story later.)
Write a scene for your WIP that you will never post/add to your story. A prologue, a different P.O.V., how your characters would react in a situation that’s not in your story, a flashback, etc.
Write down a bunch of ideas. Things that could happen, thing that will never happen, good things, bad things.
Change the weather (in the story of course.)
Feel free to add your own.