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.
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, as in:
"Now I took a left step."
"Now I took a right step."
"Now I thought it was silly to speak through my actions in my head."
"Now I giggled at myself, feeling ridiculous."
"Now I giggled more at the sound of me giggling."
"Now I quickly looked back and to the sides, to see if anyone saw me giggling and maybe thought I was crazy."
"Now I exhaled because no one actually saw me giggle."
"Now I jumped out of my pants because a fire-breathing dragon landed right beside me and tapped me on the shoulder."
"Now I screamed in terror because the dragon bit off my foot, because it said I' thinking too much, and then it proceeded to frying me ali—"
You get the drill.
Then don't touch your writing until the next day. Do nothing again if it's not happening. Do nothing until the story comes to you. Then when it does, catch it!
The more often you do this, the more relaxed you become, the easier and more enjoyable your writing process will be.