How to do password expire after 15 days?

Hello, I need to create a application wich registereds users have
yours passwords expired after 15 days in order that I can generate a
new password and send them by email.

Tanks,

Sorry, my english no good.

Your question has too wide a scope.
What part are you having trouble with? Generating a new password,
sending the new password by mail, or making a scheduler that resets
passwords older than 15 days?

Hi Sharagoz,

In realy nothing was made yet but i’m searching the best to do that. I
will try explain again.

My application have any resources that i need to share with others
users, for example CVs, but i need release the access by send data
like password and login by email, and ensure validity of login for 15
days. After 15 days will necessary contact me for reactivate access.

I think that your question is all that i need.