Address your letter to the correct department. It will probably be registration, admissions or financial aid.
Begin the letter with your tuition refund request for the current semester or quarter and include your reason. Most universities only issue refunds because of military duty, a death in the immediate family or a student's medical status changes.
Include documentation of any extenuating circumstances. Relevant documentation includes a death certificate, military orders or a doctor's note.
Make copies of the letter for your records and mail the letter, via certified mail with the signature required. This ensures the institution received the letter.