If you got hit by the New Years Do Not Disturb bug, and couldn’t be bothered taking the five seconds to work around it, then don’t worry, it’ll fix itself. Eventually. As spotted by TNW, Apple now has a support article on the bug, and apparently scheduling will kick in again normally come January 7.
The support article states:
Do Not Disturb scheduling feature will resume normal functionality after January 7, 2013. Before this date, you should manually turn the Do Not Disturb feature on or off.
To turn off the scheduling feature, tap Settings > Notifications > Do Not Disturb and switch Scheduled to Off.