So what do you do when you are "feeling" stuck and you "feel" you can't write? The operative words here are "feeling" and "feel." Feelings are odd birds: they will help you get to where you need to go, and they will make you believe something that just might not be true.
The truth of the matter is you are never STUCK. You are never stuck anywhere. Yeah, if your writing is not flowing, it might "feel" like you are stuck, but you are not, you have so many options. The problem with "feeling" like you are stuck is that it is usually connected with negative feelings, and when you feel negative feelings, it is often connected to negative thinking, which spirals back to negative feelings and on and on.
So what should you do when you are "feeling" stuck?
1. Go do something else that is FUN to change how you are feeling, and then get back to your writing. Remember you have options: YOU ARE NOT STUCK. Your writing is simply not flowing at the present time. You have a million options. Go to the movies. Get a massage. Do something really nice for yourself and when "Feeling" better get back to your writing.
2. As I have mentioned before: When your writing isn't flowing - Research. Research the time period, the setting, the history of the world you are telling your story in, and then when you get back to your writing, often you will be revitalized.
3. Ask yourself the question: Am I passionate about this play idea? Is this the most exciting play I could possibly be writing at this moment in time? If the answer is yes, GREAT, chill, relax and then get back to your writing. If the answer is no, THROW THIS PLAY AWAY, and start something new that you can be passionate about. You can get back to this play when you are feeling passionate about it again, but if there is no real crazy wonderful passion for your story idea. Give it up. Immediately.
Remember: There is no such thing as writer's block. It is simply a mental construct. Don't believe in it. Don't give it power. You made it up. Believe in your talent, your innate talent to tell your personal stories. You have options always. Sometimes you just need to change how you are "feeling" in order to get where you need to be.