Gustavo has you taken care of, but to further clarify -
You're looking in the "Photoshop Effects" section, in the bottom half of the Effect menu. In the top half you see the "Illustrator Effects".
Both sections contain an item called "Stylize". Just try the other one.
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If on a Mac, click on the main Help menu and type "Drop" into the search bar. Drop Shadow will highlight.
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To create shadows another way - create a shape and apply a Guassian Blur to it. Like Drop shadow, this will also apply a live effect which you can adjust as need be whenever you want. Use the Appearance Panel to access live effects applied to objects.
Remember, always use your Drop Shadows responsibly!
