I have done iui 15 days before and now i am having period like bleeding ,headache and mild cramping in lower abdomen?

Sorry: Sounds like you are having a period. I would do a pregnancy test immediately just to be sure. The success of IUI depends on several factors. Success rates may reach as high as 20% per cycle depending on variables such as female age, the reason for infertility, and whether fertility drugs were used, among other variables. Keep trying! Chance of success increases significantly after 3-6 cycles.