It depends on type of pills you take. If its post coital pills you should take it within 72 hours if intercourse . if its oc pills you have to take them regularly starting from 1 day of last cycle for 21 days . You should take take at fixed timing daily ,either early morning or at bedtime . consult gynaecologist for More information.

Hello if you are not planning for pregnancy der are various medications and technique you can try consult obg specialist for further evaluation and treatment.