He can click on "forgotten password" on the login page and receive a setup a new password. The validity of this email is 60 minutes by default. The user will then be able to create a new password.
If a user has problems logging in, the administrator can generate an email to reset the password to the user with a unique link which is valid for one hour. He/she can also define a temporary password for the user.
Go to the settings of the interface in the 'Members' tab.
Identify the user on the list in the 'Options' menu, and click on 'Defining a password'.
Generate an email with a reset link.
Or generate a temporary password.
Elium can also be integrated with your own SSO to prevent these password problems. Elium can even also go to automatic creation of accounts at the first login. More information here.