Adobe Photoshop CS5 saves all the steps done to an image as states in the History Panel.
Select Windows->History from the menu to display the History Panel.
Each entry of the History Panel contains a state of the image. The oldest available state is at the top and the most recent state is at the bottom of the list. To undo the changes made with the type tool, select New Gradient Fill Layer from the History Panel or type Control + Z. Clicking on any state will undo all the changes in between the newest state and the selected state. Selecting Align Vertical Centers state will undo all the states in between.
If any changes are made to the image at this point, Photoshop will delete the steps below Align Vertical Corners and replace them with the new state.
By default, Photoshop CS5 saves 20 user states in the History Panel. After 20 states, the oldest states are no longer in the list. This number of states to save in the History Panel is configurable. Select Edit->Preferences->Performance… from the menu to change this option.
Select the desired number of states and then press OK to apply the change.
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