Hello selbstmedikamentierung !

The best way to backup your UNA site - to keep the folders like inc, modules and storage and the whole database. Then you may put it back if something will happen.

But in your situation exists an interesting part like "i wanted to update my php 5.6 to 7.2. all was gone ". Your site and DB have been left, if you saw the blank pages then you need to check the error logs of your server first to find what is wrong.