can contraceptive pills fail? like "i-pill" of Cipla ?

Dear Sir/Mam,
I had sex with my wife and by mistake I ejaculated inside her without using condoms...within 2 hours of this she has taken the tablet... "i-pill" of the company "Cipla" it is a contraceptive pill...now it was the day when she has completed 14 days of last menstruation... now 4/5 days are left for the day of her next period...after taking the pill there was nothing significant difference in her behaveour or health...no vomiting...no bleeding...no pain...we are afraid... if she becomes pregnent...!! I should inform you that she had completed her last period on 17th July 2010...and we had sex on 31st July 2010...

Please help....