Repair / Fix SSH Login Publickey Error

So basically I can't log into my server.... I recieve PUBLICKEY ERROR via ssh and sftp when using root. I have tried openssh purge, reinstall, installing ssh again and so on.... I have changed passwords for root ... I have no idea how to fix this issue so that I can log into my server using SSH. Currently I can connect to the server desktop and run terminal via that with sudo commands, but I have no idea how to fix this... I need to fix the keys, ssh, so that I can login using root via ssh.