main menu and navbar in backend administrator disappear

hi, in the last two days after joomla update to 3.7.2 release and extensions update, the usual administration page looks like the attached screenshot. Main menu navbar and drop down menu are all disappear. Panic time.

So it's impossible doing any kind of operations, we have not enough joomla experience to solve this issue.

we tried to reinstall all the entire package from github, and now without the main navbar we cannot make other attempts.
By the way the frontend is working well.

we have already posted this on joomla.org forum. thanks

Roberto Angioni
https://www.eutravelin.com/