Photo Editor not starting anymore (Photoshop Elements 14)

I'm working on a Macbook Pro Retina. Till yesterday I could use the Photo Editor without any problems. This morning after I turned on my computer, the Photo Editor is not starting anymore. Organizer still works. I have no idea why this program is not working anymore, there is no error message. I can click on it but nothing happens. Is there somebody that can help me? Many thanks! Simon