What should I do with a bag left with me by someone I don't know, and a long time has passed without me being able to contact him?

If the trustee despairs of knowing the owner of the trust or delivering it to him, he should give it as charity for good causes; because money whose owner is unknown should be spent for the benefit of Muslims.

Note: The phrase "circumstances willed" is incorrect. The correct phrase is "Allah decreed" or "Allah willed." And with full respect, such a thing should not be attributed to Allah, as in His Almighty saying: ﴿And when I am ill, it is He who cures me.﴾ [Ash-Shu'ara: 80].