Had sex jan 15 & 17 without protection. i believe i ovulated jan 15 as well. i took the morning after pill jan 19. will it be effective in prevention?

Maybe. Maybe not.: Should test in 3 weeks. A urine pregnancy test done correctly gives a reliable result 3 weeks after sex (3 weeks after when conception might have happened) or 1 week after missing a period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and therefore lead to a repeat test. If a woman has her normal regular periods, then she is not pregnant.