What is the ruling on prayers and obligatory duties that I performed while in a state of ritual impurity (janabah) due to ignorance? Are they considered void? How can they be made up? Is the ignorant person excused for this, or must he repent?

Ignorance may be an excuse if it was not due to negligence in seeking the obligatory religious knowledge. If there was negligence, then one must repent and seek forgiveness. Prayers that were performed incorrectly are invalid and must be redone. This is the view of the majority of scholars, and it is the more cautious approach to absolve oneself. The method of making up these prayers is explained in Fatwa (definition) no. 72777.