Take a break, pick a few random words, and do a freewrite. A freewrite is essentially stream-of-consciousness writing for an amount of time. Do not pause to edit, do not plan out where you’re going. I personally find freewrites to be very useful for getting into writing mode. (That being said, I don’t actually use them that often.) So, if you’re stuck because you don’t feel like the words are flowing as well as they should, I suggest trying a freewrite. You might also be overthinking it, so you might want to step back and take a short break. You can always come back to your scene later.
Kill someone. Not a real person. (Seriously, do not go out and murder a real person. That is illegal and highly frowned upon.) Just pick a character and kill them off. Depending on what you’re going for and the type of story you’re writing, it might not be a good idea to kill off a main character. But, you could still kill off a secondary or side character. Feel free to be creative with their death, just so long as it matches the overall feel of the story or what you’re going for. (You might not want to drown a lead in a detailed, grotesque matter midway through an empowering fantasy, for example.) But, if the inspiration strikes, feel free to use this death as a turning point.
Cut to the villain. Or anyone not currently present. If this isn’t a good point to jump away, remember that you can always return to working on your current scene at a later time. Have you shown the villain’s perspective yet? (Should you?) What about their lover (assuming they have one)? The people they left behind? An old friend who’s looking for them? A parent following them in the news? Who else you can jump to depends on the story you want to tell. If you’re telling a story in just 1st person, you can still jump by having them recall a related memory. Or maybe a flashback. Who you cut to is really up to you.
Sketch out the ending. This could be an outline, a rough summary, or even a completed scene. The idea is that, once you have a better idea of where you’re going, you can better work with the scene you’re stuck on now. How does the current scene contribute to where the story is going? What needs to happen next to further approach the endpoint? Does a character need something special from this scene in order to advance the plot?
Change the weather. Is your character scared of thunderstorms? If your party is outside, where do they go to take shelter from the rain? Is a character fascinated by the snow? Does snow make them recall a memory from their childhood? Do someone love to go dancing in the rain? Does a sudden cloud cover send people inside? Does a windstorm force a change in route? Does a change in the wind bring in the smell of the ocean, causing a change in conversation? Is the moon covered by clouds that night? Do storm clouds cover the moon, making it pitch black outside? You probably get the idea. Weather is not just limited to the rain.
Sketch out another scene. Write it out now if you feel like it and are okay with jumping around. Or you could just outline it. This one is similar to number four; once you have a better idea of where you’re going, you can better work with the scene you’re stuck on now. What will it take for your characters to reach this other scene? Does something else need to happen between the two? How do they physically get there?
Take your main characters and use them to start a freewrite. Maybe sketch out a memory, or maybe place them in a setting they would never be in. As was stated under number one, a freewrite can be useful for getting into writing mode. In this case, you are working with your main characters. If you are writing a high fantasy, maybe put them in a modern dance club. Or in a space ship. If you’re writing a modern romance, how would your characters’ romance be different on a pirate ship? Or in 1936 New York City? Does someone go on a drug trip? What are your characters’ nightmares?
Switch your music. Play a song that matches the tone you’re going for. For example, maybe you could play music from Schindler’s List if you’re stuck on a depressing scene. Maybe some fast-pacing techno or high energy metal during a high-intensity battle scene. If one character is an angsty teenager, pick a song that you think is the embodiment of angst. If a character is feeling rebellious, then try a rebellious song.
Scrap it and start the scene over. Make sure to change something, so you don’t end up just repeating yourself. For example, maybe have an additional character present. Or have them enter the scene in a different manner. Maybe the location of the scene needs to change. Is someone hungry? Maybe have them walk into a restaurant and place your scene there. Or maybe a friend’s kitchen. What you change here is up to you. However, if you get stuck at the ‘I just don’t know what to do stage’, I would suggest making a random change and treating it like a freewrite just to see what you end up with. If that doesn’t get you unstuck, see number ten.
Lastly, and probably most importantly: question the necessity of the scene. If you’re finding yourself stuck on it, maybe there’s a reason why. For example, maybe this scene needs to go later and you’re trying to force your way through it too early. Or, maybe it needs to happen so differently that you can’t push it through the way you have it set up. Essentially, you want to examine the reason why you’re stuck and find your solution there. Do not be afraid to scrap a scene if you need to.