Started period january 19, had unprotected sex january 22nd, two hours later took a plan b. what are the chances of pregnancy?

Little chance, but..: Plan B can alter the menstrual period for the cycle in which Plan B was taken, and sometimes the next cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because Plan B works most of the time, but not all the time. One should be sure to start a form of reliable birth control if planning to have sex again, so that Plan B will never be needed in the future.