my periods date is 2nd dec but today is 12
Are your periods regular in the past? You've also not mentioned your age here.
If you haven't had unprotected sexual intercourse, then pregnancy is ruled out. The cause of delayed period in such cases are hormonal imbalance and thyroid disorder. You should be evaluated for these besides a detailed gynecology check up.
If there are no other obvious causes found, you can be treated with norethisterone pills available as Primolut N tablets. The dose and frequency will be decided by the examining doctor.
Hope this helps. Let me know if you need clarifications.
n i had regular periods in past
It's good to know previous cycles were regular. Now when pregnancy is ruled out, I would start norethisterone pills if periods don't resume in couple of days time. Should the problem recur again subsequently you need to be evaluated for other causes.
Hope I am clear. Let me know if you have any specific questions.