Suggest Cause And Remedy For Delayed Periods

Last time i had priods on 2-05-11 to 6 -5 -11 sir i had sex on 7th may night that was unprotected and on 9th june i had taken unwanted 72 pill and again on 18th may i had sex but i had taken the pill witin 2 hour on the same day and today is 12 june and yet periods not come and one more thing on 9 june i checked by prega news pregnanacy strips but the result was -ve pls doctor tell me what shoud i do