I had unprotected sex 10 days ago and my due mensuration date is 5-2-2014. But I still got no hints towards it. I took unwanted-72 in 40 hours... do I need to worry or the delay in mc is due to pill

Yes, yes and yes.
The use of emergency contraceptive can mess with your cycle.
As you had sex, of any sort, there is still a chance of pregnancy.
That being said it is still early, wait for Two weeks late and then test with HPT.

I agree, the morning after pill, is not 100 percent effective, the longer you wait after sex the less effective it is.

You can not tell now. After you miss a period and are 14 days late, you can then test