Photoshop provides plenty of safety nets for the wary user. They usually materialize as helpful dialog boxes that say things like "Are you sure you want to do this?" and "Is that what you're wearing" After awhile, they can become annoying, so if you're like most people, you start selecting the Do Not Show this Dialog Box Again Please, I Get it Already option. Thank goodness they're gone.

Then one day you begin to wonder about that warning dialog. What exactly did it say? Was it really important? Did you ever read it? Never fear, you can always retreat.

Choose Edit > Preferences > General

and click the Reset All Warning Dialogs button located at the bottom of the box. All warnings will now appear at the appropriate times. Every last one of them.