I agree with Red. Sounds like a yeast issue. But it certainly could have been a bad seal and waiting is always great advice.
Maybe you can arouse the yeast a little by turning a bottle upside down, giving it a few days in the closet, putting it in the fridge for a few days, and then checking for carbonation. Just do one bottle though.
If that doesnt work, I guess you could continue waiting (which most would probably recommended) or you could reopen the bottles, put in carbonation tablets, and reseal the bottles.