Why didn't you take it today? Why didn't you take it as soon as you remembered? That's what you are supposed to do. Take the pill and then don't miss again. If you miss your next period, then take a test--following the box instructions exactly. Otherwise, don't worry about it.

It just depends on your cycle where you were at. Lydia is correct, you should have taken it once you realized you missed it. The safest way to be sure would be to see your GYN or local health clinic.