SSH access issue

Greetings, I changed the ssh_config settings after a security advisory notification. I changed the PermitRootUser to no. Since that I am not able to connect to the server via Shell or FTP. I tried the auto fixer as mentioned above but had no luck either. I tried tweaking the settings and playing with them to figure how to connect. But no matter what I try I keep getting this message from WinSCP (for FTP conection) : `Authentication log (see session log for details): Using username "root". Authenticating with public key "rsa-key-20231109". Server refused public-key signature despite accepting key! Authentication failed.` I tried changing the values inside /etc/ssh/ssh_config file, Enabling/Disabling SSH Password Manager, also tried creating a new key (.ppk) to ensure its correct. So far I was using .ppk files to connect as I had disabled Password Authentication. But now .ppk don't work. How can I gain access to server via SSH again? - Thanks in advance for your time and effort