I am starting to use CiviCRM under Drupal 7 and feel myself still as a newbie.
I made a backup with the Backup and Migrate module of Drupal (site + DB). As a good practice, I tried immediately after the backup to restore the backup, just to learn how to do in case of trouble.
I better did not because I got the error message:
Your database is marked with an unexpected version number: 5.22.0. The v5.20.2 codebase may not be compatible with your database state. You will need to determine the correct version corresponding to your current database state. You may want to revert to the codebase you were using until you resolve this problem.
The menus of CiviCRM are now at the bottom of the screen with an ugly layout.
So backing up and restoring with the module Backup and Migrate seems to be a perfect instrument of (hopefully partial) self-destruction of Drupal or CiviCRM.
I have no idea on how to "revert to the codebase you were using until you resolve this problem". Any help will be appreciated.