From launchpad I have an email containing OpenPGP encrypted key. I received that email in gmail. But gmail wont decrypt it. Then I setup Thunderbird for gmail account and installed Enigmail for decrypting pgp key. All works fine, but when trying to open that specific message it pops up with a message
you need a passphrase to unlock the secret key for user
and give a password field to enter. But my root password or mail password anything won't work there and I am not clear about this passphrase.
However, what can I do now?
gpg --list-secret-keys
in the terminal (as regular user) to list your private keys. Try to remember the passphrase you put on it.