Are you talking about the notifications, do you you have them turn on in settings. Or are asking if you can restore notifications that you have cleared.
To assist taz if he does not mind because he asked a good question. You are not going to get back ANY notifications received and cleared or deleted. You are only going to be able to turn on the sections in your settings under Notification Center on what you want to see or not. Hope you don't mind taz in helping a bit.