Retrieval

I have a membership part to my website.

Its a fairly basic membership script.

The information users put in to register is basic name, email..etc

The only thing is, it doesn't have a Lost Password retrieval part, nor does it have a section where users can change there information, such as password.

I would like to create a simple script which will do this.

I need a script that will retrieve the users password from the database, upon the request of the user by entering there email address.

I also need a script which will retrieve, and edit the users information to the database.

Any help?