He took some money unlawfully. How should he repent?
Question

                He was employed in a government department, and some income came to him in an unlawful manner. Then Allaah guided him. What should he do about those things that he has spent in an inappropriate manner, knowing that he does not know how much there was?.
Praise be to Allah.He has to return what he took from each 
    person to its rightful owner, if he can find him or his heirs. If he tried hard and could not do that, then he should give the money in charity 
    with the intention that it is being given on behalf of its owner. 
And Allaah is the Source of strength.