Your site’s database seems to be having issues.
If you have no clue what to do, please contact your hosting provider (perhaps OVH) for help.
NB: As an aside, note the your login for your own site is totally separate from your login here at WordPress.org. But you need your site working before you can enter the login credentials.
thank you for your reply I have contacted OVH and they said the error is related to a database password mismatch issue, and I need to check on the CMS but how can I access my dashboard if the page is not reachable , my site is totally fine on OVH side ( server, hosting.. ) no issue at all..
I need to check on the CMS but how can I access my dashboard if the page is not reachable
No, you don’t, and cannot, do this from the WordPress dashboard
The database connection info are in your site’s configuration file named wp-config.php
.
This file is normally at the root of your WordPress installation — which is on your hosting server. That’s why I directed you to your hosting provider, but, apparently, they don’t offer any such support.
Use either FTP or your hosting control panel’s File Manager to locate and edit this file to fix you database connection details.