Recover EC2 .pem file?
Solution 1:
It is my belief that for security reasons you are not allowed to do that. My guess is they probably don't keep the private key on their side either they just generate it, get the public key and save it and then allow you to download the private key.
So... bottom line is... No, you cannot download it again. Your only option is to create a new key-pair and start your instances again using this new one instead.
Hope this helps.
Solution 2:
It's your private key and used to authenticate you to the server. You've effectively lost your password...
Solution 3:
You can go to the EC2 Management Console, create a new keypair, create an AMI from the volume of your instance, and launch a new instance from the AMI with the new key pair.