If you are more than 12 hours late with a pill they are no longer effective. You need to take the next pill on time and continue this for 7 days before you will be protected again. During this time you should use an alternative form of contraception, like condoms.
Taking more than one pill per day is not recommended, and may even result in nausea and/or withdrawal bleeding, so stick to just one a day even if you missed several!