I too have the same problem. I am not a techie - I can do the basics on blogs and that's about it. Even some of what is written above is beyond me.
Yesterday I was prompted to update my MYSQL database, having been told mine was out of date or words to that effect. I did so and a message came up showing a couple of error messages (I did not record these) but underneath it read something like .. "if you have completed this step and can read this message then this has updated successfully. That is all you need to do".
I have about 20 blogs on different subdomains but my main work-from-home blog is the only one which seems to have come up with the same problems shown here .. I believe as a result of the upgrade. When I go to publish a post I cannot - instead it is just saved to drafts and after hitting "publish" a blank screen comes up. Furthermore when I go to delete a post I find I cannot. I went to see what would happen if I went to create a new page ... same problem. Just a blank page and then I noticed that all of my Pages had been wiped away (not my posts).
This is occurring on just the one blog - as I say the others seem to be OK. But it is my central hub of operations, so if anyone can tell me how to fix this problem I would be most grateful. If possible in layman's terms. It is critical I get this back up and running properly, asap.