As an admin, you also have the option to help users who have problems to use the functions to retrieve their login details.
You can send them their user name and a new password via e-mail.
Please go to:
Overview => User and Participant Management => List of All Users
Search for the corresponding user, click on his or her name to access the user details. On the user detail page, in the box "Action" click on the link "Send Password to User" to send the account details to the user (see image). The user will receive both the password and the user name in one single e-mail.