What is your usual menstrual cycle length? If you have had unprotected intercourse in between and you are not on any birth control measures, this can be a possibility that you are pregnant. Get yourself tested for the same to confirm/rule it out.
but my temperature is dropped after 2 rise and stayed low.My cycle length is 40 days.But I hv PCOS.so is it possible that I am pregnent with no rise in temperature in second half of the cycle.