What is the ruling on money taken by the questioner from an unfamiliar woman, which he wishes to return to her, but she does not respond to him, and he feels pangs of conscience and divine punishment for it?

You must return the borrowed money to its owner, unless she absolves you of it. If you find no way to return it and you contacted her and she absolved you of it, then you should give it in charity on her behalf. If she contacts you after that and you inform her of what you have done, then if she is pleased with the charity, your obligation is discharged. But if she is not pleased, then you must return her right to her, and you will be rewarded for what you gave in charity.