When you open the file click on the arrow in the lower right-hand portion of the ribbon labeled "Styles". Once the (empty) styles menu appears, click on "Options" in the lower right-hand area of the menu (this will open the "Style Pane Options" menu). Using this menu make your selection for how you want to view your styles (ensure that you check all of the check-boxes). The styles (based upon your selection of "Select styles to show:" and "Select how list is sorted" will now be displayed.

Hope this helps.