Losing an object is read as fear of losing what it stands for — security, identity or a connection. Dream books ask what the lost thing means to you.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.