changes disappear

Since yesterday, I’ve been unable to make any changes (other than to the theme) in my posts.
When I insert photos into posts, they disappear from the editor upon update and definitely don’t appear on the site. Changes to text don’t take affect.
If there was a “save changes” button, it’s now missing.

I deactivated/activated all plugins and loaded the Twenty Eleven theme; this had no affect.

I can’t figure out what has changed or why my changes disappear. I did notice, however, that when I load the site via firefox, it says “the quicktime plugin crashed.” I don’t know whether this is related in any way.

Here’s my website: https://www.merrandrog.us