Have you looked at the Administration module? It should be included in your project by default and be located in the App Store modules.
You can use the forgot password module from the appstore for this.
The module has the option to create the signup logic as well.
Or get some insights from this module for your own functionality.
I used the administrative module. My created accounts are save, I just don’t understand how i can add custom logic to the sign in page (see attached) to retrieve data from the created account.