Why did King Artaxerxes ask Nehemiah what was wrong?

Answer: His face was sad

Nehemiah had never been sad before the king, who asked why his face was sad though he was not ill.

“Now in the month of Nisan, in the twentieth year of King Artaxerxes, when wine was set before him, I took the wine and gave it to the king. I had never been sad in his presence, so the king said to me, “Why is your face sad, though you are not ill? This could only be sadness of the heart.” I was overwhelmed with fear”— Nehemiah 2:1-2 (BSB)