"Julia does not sleep on the bed."
Translation:जूलिया बिस्तर पर नहीं सोती।
नहीं always comes before the vetb. In your example, दरवाज़ा बंद है, there is no नहीं nor a verb. If you pertaining to the sentence दरवाज़ा खुला नहीं है, there is still no verb here because खुला is used here as an adjective. It's a state of being. It pertains to the door, which is not open. It can be a verb though eg. वह दरवाज़ा नहीं खुल रहा है (The door is not opening).