What should I do with the amount owed to a foreign worker who disappeared after an inspection campaign revealed the presence of pornographic films in his room, and I do not know the exact amount?

You must strive to give the fixed money that is your responsibility to the man, even if he is a sinner, because his sin does not negate his right. If you cannot determine the amount, estimate it approximately, erring on the side of caution, by analogy with previous months. If you despair of reaching him, then give the money in charity on his behalf. If you meet him later, give him the choice between approving the charity and its reward being for him, or returning his right to him. If he chooses to approve the charity, then praise be to Allah. If he refuses, then you must give him his right, and the reward of the charity will be yours.