Question: What is the ruling on a person who was forced to break their Sawm (Fast) during Ramadaan and forgot to make up for that day, but remembered after about four years? What should they do in such a case?
Answer: Whoever breaks their Sawm during Ramadan for a Shar`ee (Islaamically lawful) excuse has to make up for the days missed even if many years have passed. If this delay was not for a Shar`ee excuse, the person in question has to feed a needy person for each day missed an amount of half a Saa` (1 Saa` = 3 kg. Approx.) of wheat, rice, or any of the staple food of the country… read more here.