I have a Nokia Lumia 525. When I get a toast notification, it disappears within a second. If I want to see this notification again, what should I do?
If your Lumia is running Windows Phone 8.1, you can swipe down from the top of the display to reveal the notification centre, which contains all toast notifications. Tap on any entry to go to the respective app, or swipe right to dismiss.
If your Lumia is running Windows Phone 8.0, there unfortunately is no way to recall toast notifications. Your only hope is to have the respective app pinned to the Start screen, in which case its live tile should update to indicate that it has new content for you.
For more information on using the notification centre, see the official how-to at WindowsPhone.com.