Restore a copy of the encrypted database
I have encrypted the backup using the method followed by the file server.


Not sure what that means.


  Unfortunately, I did not keep a copy of the certificate of the process of encryption and unfortunately also the server was completely destroyed and is impossible to run again and I have to restore a copy of the database.


That's going to be impossible. If you don't have the encryption cert, you can't restore.


  I have a copy of the rule but it is encrypted.


Rule? Not sure what a rule has to do with this.


  Is there a solution to this problem?


Tell the people that you can't restore the database and it is lost forever.