You can email the user a one-time token for setting a new password.
You should never store the users password.
You should never store the users password.
In addition the reset password is not possible when the data is encrypted on the client side. This is how TrueCrypt works - if you forget the password, all your data is lost.
"Users are able to login to servers, and encrypt all their data, without ever exposing their password or encryption keys to the server."
"And if the user's data on the compromised server is encrypted using the user's keypair, then even the users' data is still protected."