What do i do? Zelda minish cap?

im at the part wen youre collecting the missing library books and the walkthrough went to the house that is to the east of the market of castle town then down the steps and so on... so i went there and the guy says that he's busy and nont to disturb his research but the walkthrough guy went in his house and put out the fire in the fireplace and turned small and went up the chimney, but as i said, he won't let me in his house to put the fire out. HELP!!