My last period started 3/15/15 i took a preg. test on 04/26/15 and came neg. why has my period delayed so long?

Probably benign: There are many reasons for missed cycles. Stress, weight loss, medicines. And, of course, pregnancy. It is pretty common for women to have occasional irregularity in the lengths of their menstrual cycles and this is most likely that. However, I'd definitely repeat your pregnancy test to confirm it is still negative. If 3 months go by and you still have no period hormonal test are in order.