No images displayed at all

I've been trying to find a solution to this problem, by trawling through issues here and through google. However no one seems to have my specific problem, so i'm hoping it's just a quick fix.

There are no images displayed on my gallery page, at all. I've uploaded the images to the correct folder. When i "manage galleries" i can view all the images, however, the checkbox is not ticked and the word "visible". I try to check the box, it says "saving..." but never saves, i assume, as it just stays on "saving..." forever. I'm assuming this is the problem? Does anyone know how to fix it?

Thanks.