As this is a personal question that needs to be based on your experiences, we cannot provide the whole essay for you. However, we can use an example in order to show you how you can begin your work.
In this text, you are asked to write an essay based on an experience in which you needed to adapt to a sudden change. An example of this would be moving somewhere else. You then have to divide your experiences in a way that matches the structure of the narrative (beginning, middle and end). For example:
Beginning
I had spent the first 13 years of my life in California, and because of this, I had always taken it for granted; I had never imagined that I might have to leave. But when my dad was asked to relocate to Arizona, this became a reality. When I first heard the news, I was devastated. But soon, I realized I needed to come to terms with this change.
Middle
I had to tell all my friends, and say goodbye. This was very sad and painful. However, we promised we would stay in touch, and maybe even visit each other. I also had to clean out my locker and pack eveyrthing in my room. I tried to cope with this change by learning more about my new town and school, and by trying to imagine what Arizona was going to be like.
End
In the end, the move was reasonably successful. I still missed by friends a lot, but I was able to make some new ones. I also joined the soccer team in my school. My family was able to get a larger house with a garden, and we even adopted a dog! I am planning to visit my friends in California next summer, and until then, I am enjoying my new life in Arizona.