Change password is an action related to a particular user account. Change password widget only gives the possibility to input the new password and in order to do this it needs encrypted query parameters to find the correct user and to validate - the specific user has requested this action.
To do this, the user that clicked on the link: Forgot password?
(in Login widget), receives an e-mail with a personal URL link, that leads him to the Change password page. The link contains the user-identifying query parameters.
All this step-by-step setup is explained in our documentation: http://docs.sitefinity.com/change-password-widget
Let me know if you need more help on the topic.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items