Access the Student Federal Aid's PIN page at http://www.pin.ed.gov/PINWebApp/pinindex.jsp. Find "Request A Duplicate PIN" on the sidebar to the left and click on it.
Fill out the form. Here you will find a form containing questions regarding your Social Security number, name, and date of birth. Fill these out accordingly. Select "Submit Request" at the bottom of the form.
Answer your secret question. The next question will be a "Challenge Answer" which you had set up when first applying for your PIN. Fill in the form and then press "Submit Request".
Get the PIN. You will now be directed to a page to retrieve your PIN. You may choose to display it onscreen immediately by selecting "Display Now", receive it in an email by selecting "E-mail" or have it sent to you at your mailing address by selecting "Postal Mail". Choose your preferred option in the drop down box to the right and select "Submit Request".