What's wrong is that you haven't given us any information to help you.
Nevertheless, here is my wild guess. You are a Mac user and you have just updated to Sonoma. You are trying to run an older version of Elements which is not compatible.
Rather than make this a guessing game, tell us as much information as possible, including whether you are talking about the Organizer, the Editor or both, whether you are receiving any error messages, and what happens when you try to launch the program.