What should a person do who, in old age, wishes to redress injustices, but cannot recall whether they took anything wrongfully in their youth, and will their Lord punish them for what they have forgotten?

May Allah increase your eagerness for good. The fundamental principle is that your conscience is clear, and nothing is binding upon you. Therefore, you should frequently seek forgiveness, perform good deeds, and adhere to the Sacred Law as much as you are able, striving diligently to please Allah the Almighty. And have a good opinion of Him, Glory be to Him.