We're using SSO so we don't see the login screen, but I know there is a 'Reset Password' option in the Security section (under General tab) in the ACP. You might want to give this a try.
What do you mean by not working?
If an account is locked out the reset functionality indicates request sent, however email is never received. If account is unlocked by admin the functionality resumes. I believe this is working as designed. Seems strange though as generally people try until they lock their account and then need to reset.