That's not enough information to work out what the problem might be.
I have reset the password and emailed it to the user. If the problem is their email address then they'll need to contact us directly. Giving out passwords for one user to pass along to another user would be bad practice.
EDIT: If the user hasn't seen the new password I sent they should check their spam box.
I tested password reset emails, they are working fine so far as I can tell. I don't have a ton of email addresses to try from, but those I did got the message almost instantly.