Creating a website for reset the password if authenticate user.

Hello,
  I am creating a website for reset the password in one of the application from the back end.
 
I have created a webpage with only one button called "RESET".
If user click the button, it should check the user have already access the application from the "USER" table. If no access, the message appears "You do not have an access."
If yes, next step whether the user have authenticate. If yes update the encrypted password from new table called "UMRESET" to the application table "USER" password.
Please help me create this webpage.
 
 
Thanks
Nihar
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