How can twenty years of invalid prayers due to ignorance be compensated for, and will Allah forgive this sin?

The madhhab of the majority of scholars is that whoever does something that invalidates the prayer, being ignorant of having omitted a pillar or a condition, is obligated to repeat it, because it is a debt upon him. Shaykh al-Islam, however, holds that there is no obligation for qada' (making up) in this situation. Making up the prayer should be done according to one's capacity and in a way that does not harm the body or livelihood. Repentance and seeking forgiveness for the shortcoming in learning the rulings of Sharia are also obligatory.