Aww, I'm terribly sorry for that. :( I'll be looking to fix that. Do you remember how many frames and layers did you have? Did frames was detailed (a lot of pencil strokes)? Are you using incognito mode, or did you cleared browser cache/history? Try to not clear anything and just add new frames/layers. There's a chance that only information about number of frames/layers was deleted, but images are still there. Also try to use https://flipanim.com instead of http://flipanim.com (and vice versa). Animation on first is not visible on the second (due to security reasons).