Retrieve old lock screen notifications
Apple messed up, in my opinion, by taking away the "missed" tab on the notification pull down in iOS 8.   

The only thing I've found that helps is to navigate to settings > notifications and set "sort by time".   After that you can pull down the notification center, and the notifications will still be grouped by app, but at least they are sorted so the most recent group is on top, then you can scroll down reading the top notifications out of each group until you get "caught up"

Personally I used that "missed" tab more than almost another screen on the phone, I can't believe they eliminated it.