If I was unaware of Ghusul al-Janabah due to my young age and learned about it years later, do I have to repeat all my prayers and redo every year of Ramdan fasting?
If you could ask about your religious responsibilities and rules but you ignored to learn,you then need to repeat every Prayer and fasting done with out proper purity from Janabah.
If you had no way at all to ask or learn your religious responsibilities, then you do not need to repeat.
This
Wassalam.