How to tell the user what their options are when they forget their password and there is not the option to reset it through the web or email?

There is a system where users can set a web password through the application they have on their cellphones. So if they forget the password they can easily reset it through the app with no problem. Another way to reset a password is to call the support center, and they create a password and text it to the user. For some reason (for one I can say the users don't use their email to register), there is not the option to reset or send the password through the email. So, what should be done? How should we inform the user that if they have forgotten their password what the options they have are? Here are some solutions coming to my mind:

• A link saying "Forgot password" to another page explaining the options to them
• A button saying "what to do in case of forgetting my password" or something like that and by clicking it a message shows up in place explaining the options the user has.
• As the options are limited, always show them under the login button