unactivated users

I have a user who has not activated there blog yet, but has received an activation email. He is using his designated username and password from the activation email and is not able to access the blog...says his password is wrong. Is there a way to resend a password? Right now, it says that their email already exists. However, I am not able to resend his password to him or access the original email that was sent. Any suggestions on what to do?