What Causes Delayed Periods Along With Abdominal Pain?

I am 23 years old. I didn't marry, I had a sex with my boy friend on december 7th , My last finishing date of period is december 5th. But now it is January 7th I didn't get period. I am very much frightened whether i am conceived, even i had a a pappaya yesterday. I have a bit of pain in my abdaman. I don't want to get a baby now. How can i abort it in the house itself. Is their any tablets. kindly help me plz....