I hate this place. I just logged in and wrote a comprehensive response to your post which I now have to repeat because yes, it didn't post.
I too have lost something from my blog. A whole month of posts from Jan to the start of Feb. are gone from the blog even thought they are still listed as posts on my manage page. I can access them for editing but when I preview them they come up in a page that is for commenting.
I think the culprit is the fact that wordpress.org apparently believes it needs to update constantly. We the user then have to juggle the three service or more which we are using in order to self-host our blog.
I say or more because I include the plugins we need to do just about anything. For example, the add a video button doesn't work. You need a plugin and it has to be compatible with your wordpress version. Meanwhile, your hosting services are also upgrading.
It is a mess. Which is why I have backed up all of my posts and am thinking seriously about moving to blogger.com where you only need the one host to do business. I know the editor there isn't as smooth but at least you can trust that when you have an add a video or audio or image button it will work for you.
I will follow this thread to see if anyone from the wordpress.org side responds.