What is the ruling on someone who sees a paper on the ground, does not know what is written on it, and leaves it? Does he become a disbeliever if it contains the name of Allah and he is unaware? And is his fasting accepted if he was fasting on that day?

Whoever sees a paper and does not know that it contains the name of Allah, or does not strongly suspect it, is not obligated to pick it up or inspect it, to avoid hardship and difficulty. Some scholars have mentioned that the solution to the problem of scattered newspaper pages is to ignore them while spreading Islamic awareness. Therefore, whoever leaves this paper and does not pick it up does not sin and does not commit disbelief. As for fasting, leaving this paper has no effect on it, for sins do not invalidate fasting, even if one knows that it contains the name of Allah, so how much more so if one does not know. The acceptance or non-acceptance of fasting is a matter for Allah Almighty.