but all arguments and excuses will by then have been erased from their minds, and they will not [be able to] obtain any [helpful] answer from one another.

Then the (whole) story that Day will seem obscure to them (like light to the blind) and they will not be able (even) to question each other.

On that day (all) tidings will be dimmed for them, nor will they ask one of another,

On that day excuses will become obscure to them, so they will not ask each other.

But the information will be unapparent to them that Day, so they will not [be able to] ask one another.