Are you sure that you have the correct MySQL database username and password in the wp-config.php file?
Are you sure that you have typed the correct MySQL database hostname into the wp-config.php file?
If yes to both, then you’ll need to contact your hosting provider’s support to ask why your database server is offline.
No I am not sure and I have no idea how to access that file.
No I have a new SQL. How can I update it when I cannot access my dashboard?
Access your server via SFTP or FTP or a file manager in your hosting account’s control panel (consult your hosting provider’s documentation for details), and edit your wp-config.php file with a plain text editor.
More details on working with that file:
Thank you! My non-tech self managed to follow your instructions and it’s fixed 🙂