I used to fling out my arms in despair over my keyboard. Or start Wikipedia surfing, which I don't recommend because it led me down this wormhole of understanding R. Kelly's rap opera "Trapped in A Closet." Once I even attempted a "words summoning" dance, which involved prancing in a circle carrying a bunch of sharpie pens and chanting.
It didn't work.
Now, I try switching up the perspective and adding facets to whatever isn't working even if I know I won't keep what I'm writing. If it's a fight scene and there's bloodshed, I'll try to jostle up some words by writing from the POV of the blood. Weird, yes. But sometimes it yields a sense or image or moment you didn't anticipate. Perhaps it's the horror when no blood sinks into the ground because the earth has already drank up so much. Maybe it's the smell of something, not just sweat and iron, but rose and salt. It helps me push the scene a little farther.