after sex my girlfriend took i pill but 15 days later she had no period?

Hi Siddharth,

It means - NOTHING.

Taking the Ipill an make a woman's next several periods early or late.  There is no indication that the Ipill has or hasn't worked.  It's only about 86% effective at preventing pregnancy.

She CAN take a home pregnancy test, using her first morning urine.

Good luck.