Messed up "Edit page" and "Edit post" pages' screen (missing buttons, …)

Hi there,

I’m having problems with the appereance of the “Edit page” and “Edit post” pages in the WP backend. Edit buttons are missing and the title field too.

Here you can see a screenshot:

https://www.dropbox.com/s/l103ju6mtdm6lzs/screenshot-backend-2015-10-13.png?dl=0

Things I did to try to solve the problem:

? Activate the Twenty Fifteen theme instead of the one I was using (SeaShell)
? Deactivate all the plugins
? Uninstalled all the plugins
? Re-install the WordPress 4.3.1 files

The problem is on this website: ericavagliengo . com

Any idea of what could cause the problem? Could it be connected with a “dirty” DB?

Thanks a lot to anyone that could help!

Simone