help - my images have disappeared!

I’m a new Harmony user (I’m trailing premium v15.) I’ve been building an animation for a university assignment and reopened my project to find all the visuals missing. The rigs, nodes and keyframes are still there and any new images (AI files) I import are visible. The only thing that I can think of that I did was move the original source AI files into a different folder, but moving them back to the desktop hasn’t worked. I’m up against a deadline and would really appreciate any advice anyone can offer!