Hi & Welcome. Primolut N (Norethisterone) is Progesterone only pill, it can help you as a birth control pill if taken regularly & started on the second day of the menses to get the protection against pregnancy. However it may not prevent pregnancy since your ovulation has taken place today. You are advised to consult a gynecologist for an emergency contraceptive pill like I-Pill which if taken within 72 hours of an unprotected sex can prevent pregnancy up to 95% by preventing of implantation of fertilized ovum in uterus. It has better results if taken as soon as possible following a sexual act. Hope this answers your query.