Access denied for apparently no reason

I have an EC2 Linux Debian server, where I perform some tasks through the PUTTY console, however, a few days ago I can no longer access the server using my credentials that I have always used.

1: I no longer have the .pem key as I am the new developer at the company.

2: only I have access to the credentials and they have not been changed (I even received the same message from AWS support).

3: I would like to look for an alternative that would not require a server migration, since this is the production server.

What possibilities do I have to change the server password, or what can be done to give me access to this server again?