What did Hezekiah do when Isaiah told him to put his house in order?

Answer: Turned to the wall and prayed

Told he would die, Hezekiah "turned his face to the wall and prayed to the LORD."

“In those days Hezekiah became mortally ill. The prophet Isaiah son of Amoz came to him and said, “This is what the LORD says: ‘Put your house in order, for you are about to die; you will not recover.’” Then Hezekiah turned his face to the wall and prayed to the LORD,”— Isaiah 38:1-2 (BSB)