Allow the story to come to you, not the other way around

Don't force it.

When stuck or unsure or lost, close everything (your laptop, your notebook, your skull with your pulsing, jittering brain) and WALK AWAY INTO SILENCE.

Whatever time you have planned for writing, fill it up with doing nothing.

And I do mean exactly that.

DO NOTHING.

If it's hard for you, then focus on your breathing. Listen to your breaths. Meditate. 

If meditation is not something you know how to do or want to try, speak in your mind through your actions, to the point of silliness,...