Are the prayers and acts of worship of one who was ignorant of the rulings on major ritual impurity for a year and a half valid, and must he make them up or offer expiation now?

Scholars have differed regarding the obligation of making up (qada') prayers for someone who unknowingly omitted a condition or a pillar of the prayer. The majority (jumhur) held the view that making them up is obligatory, while others held that it is not. The opinion that it is not obligatory has some strength, but it is more cautious to make up the prayers for the period during which ghusl from janabah was unknowingly omitted. This making up should be done according to one's ability, in a way that does not harm the body or livelihood. As for fasting during those days, it is valid, because janabah does not prevent the validity of the fast.