Many of our memories come from times that hurt us or made us cry. Not having a voice is one. Don’t think about when laryngitis stole your voice, but when someone chided you or told you to be quiet.
The first time might have been when you were quite young. For example, a teacher called on you to answer a question and then didn’t like your response. How did that make you feel?
Maybe it occurred at home. You used words that angered your parent and were disciplined in response. What was your reaction? Did you quit talking? Or continue to speak your mind even though it caused more criticism to come your way?
Your task is to describe that time in your life when you were silenced, for whatever reason. Place yourself in the setting, then describe it in such a way that your readers will know where you are and what you are doing.
You can write from your memories or create a scenario when something similar happened to your protagonist. The important thing is to evoke those emotions that arose. The reader needs to feel the pain, the hurt, the frustration, the anger.
Reread. If those feelings do not come forth, then add details to enhance the experience.
Have fun with this one.