Anytime you forget to take your pill you could potentially become pregnant. In this case, you should have taken Plan B to help prevent becoming pregnant. Since it is too late now, if you miss your next period, take a pregnancy test.
*If you are having a hard time remembering to take your pill, there are other methods that you do not have to take every day. Patch (1 week), vaginal ring (1 month), shot (3 months), IUD (3,5, or 12 years), or implant (3 years).