amazing answer broi believe this is not possible,
1) but you can make a clone for the server, storage the tempalte, launch new one, whit new pem file, connect to the server check if all is good and delte the other one.
2) deatach the disk, atach to another instance, allow root login and make password in the user, detach and reatach in the first server, done
likely i got the PEM file somewhere in the disk but i'm sure this will help to retrievei believe this is not possible,
1) but you can make a clone for the server, storage the template , launch new one, whit new pem file, connect to the server check if all is good and delete the other one.
2) deatach the disk, atach to another instance, allow root login and make password in the user, deatach and reatach in the first server, done
in the disk of the server? if is this the case, jsut deatach and reatach to another instance and search find . -name myFile.pem (ssh) in the / directory of the other disk, if is in your windows use the same but whit *.pem in C:/likely i got the PEM file somewhere in the disk but i'm sure this will help to retrieve