Password never arrived after registration

I have created a blog website using WordPress and user can only post or comment after login.

1. I click “Register” in the wp-login screen, it prompts for entering username and email address. After enter the data I click “Register” button.

2. A successful message “Registration complete. Please check your e-mail.” was displayed. However, the password never arrived in the email address that I had entered after days.

Can anyone help me in this? Thank you.

jjlondon