i'll bring the bread because boy, you're the jam by scagnetism 

 Length: 8k 

Just when he’s about to stop clicking the next button and claim defeat, maybe put some posters up around town, he’s met with a picture of white cardstock lying on a table, words written in black Sharpie with careful, deliberate strokes. “Hiiii,” it reads, “if you’re reading this, you’ve found my camera! I’d love it if you could contact me so I can get it back. It’d be the nice thing to do.” 

 Or the AU where Harry loses his camera. Louis finds it. They fall for each other via email.