Page edit has stopped working

I created this site just over a year ago. For some reason I can no longer edit some of the pages. When I go to some of the pages the menu at the top of the page which includes the “Edit Page” function doesn’t appear. If I try to edit the page through the dashboard it lets me do it, but the changes don’t seem to take effect.

The page I need help with: [log in to see the link]