Hi.....I Had Unprotected Sex On 24 Th Jan By 5pm

Hi.....I had unprotected sex on 24 th Jan by 5pm and I took unwanted 72 after 2hours....BT till now my period does not come out...last time when I took I pill my periods come out within 3 days....I m worried....I am thinking of taking another pill...is it necessary? What should I do? If periods come then is there any chance of pregnancy? Plz reply as soon as possible