Did unprotected sex(13june),took ec pills. i got my periods on 20june (expected date)is there stil any chance of the getting pregnant due to this sex?

Sounds like no: If you had your normal period at the expected time then you are not pregnant. If you are not certain this was your normal period then you can always check a home pregnancy test about 2 weeks after intercourse.

Pregnancy test: The only way for a woman to be sure that she is not pregnant is by doing a pregnancy test.

Yes: Not all bleeding is your period and even if you took the EC within 24 hours it is at best 75% effective. Most patients have some bleeding about a week after EC use, which is not necessarily their period. I would check a pregnancy test in another week and its probably time to consider a regular birth control.