Had you bothered to put forth a little effort and do a basic web search or a search of the forums there would have been no reason to ask that silly question.
You were capable of finding these forums, signing up to post, and posting, certainly you can put forth the effort to do a search before posting any other silly questions.
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.