Without knowing what caused this, it's irresponsible to blame concrete5. Server upgrades, php upgrades, database engine failures at your host, etc, etc are much more likely to be the culprit and would have killed any database-driven site built under any framework.

But I don't think it is normal to reinstall Concrete5 and upload what was a very functionnal DB from a previous date without problem, but Concrete5 do not see any page from that DB.

To properly restore any database-driven website, you need to have a copy of the DB AND a copy of the files that were backed up together, at the same time. If you have a copy of the database that doesn't match the files then it will fail. This is because the tables in the DB says that certain add-on are installed and expects to find those add-on's files on the server. If you re-installed concrete5 from scratch, I'll bet that some of the add-ons were not installed when you tried to restore the mis-matched DB. This is not a concrete5 problem. It's a problem with all database-driven frameworks just like Wordpress or Drupal.

Try re-installing concrete5 and add all the add-ons that were installed when you made the DB copy. Then try to restore the database.

I reinstall all add-on previously installed and the re-upload the data base and I get this error message:

"Erreur
Requête SQL :
-- Table structure for table `AreaLayoutColumns`
--
DROP TABLE IF EXISTS `AreaLayoutColumns`;
MySQL a répondu: Documentation
#1046 - No database selected "