You must apply to the Immigration and Naturalization Service for reinstatement to F-1 student status if you have lost your F-1 status by any of the following actions: You did not carry a full program of study You did not attend school during a fall or spring semester, unless you were excused for medical reasons You remained in the United States beyond the time authorized under duration of status and did not apply for extension of stay You violated the immigration regulations in any other manner