Never forget that you can always write about your past.  Just ask yourself some questions.  Like these:

Write about a book that influenced you, such as Catcher in the Rye, or For Whom the Bell Tolls, Gone With the Wind, The Grapes of Wrath, To Kill a Mockingbird, Catch-22, The Color Purple. How old were you when you read this book? Did this book change your opinions or beliefs? What did it teach you? Did it motivate you to action? Did it challenge you, or did it affirm and resonate with your own experiences? Did it surprise you? Did you recommend this book to others, or discuss it with others? Was this book recommended to you? Or was it a “forbidden” book? Did the book live up to your expectations, or surpass them? *

* Excerpt from Making History: how to remember, record, interpret and share the events of your life. More lists of questions like this can be found in that book.