What does it mean when you get sore nipples a week before your period and then not get your period?

Congratulatuons! You're pregnant! There are other possibilities but the most likely one is pregnancy. Buy a pregnancy test. Whether or not the test is positive you should see your on/gyn.

Related Questions

Can you have sore nipples and not get your period?

Possible. It is possible to have sore nipple form an infection or a trauma to the breast.