I hope you’re talking about keys & ID’s, not friends! If you’ve lost someone close to you, I’m so sorry. You have my deepest sympathy. If it’s little things, it’s probably just a moment of inattention when you set them down, distracted by more interesting elements of your life. One of my assistants finds it helpful to say the location aloud when they set something down, e.g., “I’m putting my ID on this table.” If you lost something in the library, try the main circulation desk on the 3rd floor; that’s where lost items can be found.