Plan B Pill Failure: Understanding Effectiveness & Next Steps

Question
Hello,
I had unprotected sex with my boyfriend on 7/2/10 (around 2am). I am on birth control but didnt take it for a couple of days after my period because I didnt realize it was time to start the cycle again and I needed a refill.
I got the plan B pill later that day, around 2pm. It was Next Choice (levonorgestrel) tablets .75 mg, where I take 2 pills. So I had to take the other one at 2am. However, I lost the second pill.
What is the severity of this? Do I need to go get the Plan B pill again? Or since I am now on my Birth control again and taking one pill be okay?
Thank you for any help.
~KW

Answer
Assuming you started your pills 2 or more days late, you're not protected by the pill until you've been back on it for 7 days.  Since you missed the second dose of the Plan B, I think you're only half way protected by that.  If you want to be pretty sure you don't get pregnant, I would get the second dose of Plan B.  In the future if you take Plan B, take both pills at the same time.  It works the same, and you won't lose the second pill.