Life is a huge collection of writing prompts. That's why every creative writing teacher I've ever had strongly suggests carrying a notebook everywhere I go. If someone handed you this picture and told you to write a two hundred word story about it, would you, could you tell a tale?
Images are all around us. We just need to pay attention and let our imaginations take over. Who do you think is under this umbrella? What are they talking about? Where are they? Why are they together?
Try picking out a random prompt: something you see out the window, a picture in a magazine, people walking down the street, sitting on a park bench. Go ahead. I'll wait...