AWS EC2 Linux web server can't login

Hi Freelancers, We have an Amazon EC2 Linux server - Red Hat which is running a web-site. The web designer told me that his FTP access stop working. I then asked the "sys-admin" who helps us manage the server to look at it, and he says that he can login with ftp user, but then there's something with permissions of folders and the user doesn't have access.. something like that... he was doing additional diagnostics regarding that. Here's the current issue: We usually logged in to server via Putty/ssh and also used .ppk file since AWS seems to require that. Now, we can't login to the server anymore. We always used to login with username: ec2-user , and then we can switch to Root user. But now, when we try to connect with Putty/ssh, and type in username: ec2-user, the ssh terminal immediately says "Server refused key" , and Putty says: "disconnected: no supported authentication methods available" . If i try the same, and try to enter "root" username, it says: Authenticating with public key "imported-openssh-key" Please login as the user "ec2-user" rather than the user "root". Then it just closes. I don't know what may have caused this. The web server is still running just fine, but we can't login to it anymore (as described above). We do have full login to AWS EC2 Console. We need help with the following: 1. Diagnosing this to see what have happened 2. Restoring our Root access and creating FTP user so it works properly 3. Creating an FTP user and make sure it works properly 4. Offer options to set-up automatic daily backup of the server, set-up the backup and show how to backup/restore. Looking forward hearing back from you!