Viewing layer comps
To view a layer comp, you first need to apply it in the document. In the Layer Comp palette, click the Apply Layer Comp icon 
next to a selected comp.
To cycle through a view of all the layer comps, use the Previous 
and Next 
buttons at the bottom of the palette.
To cycle through a view of specific selected comps, select the comps in the Layer Comps palette and then click the Next and Previous buttons at the bottom of the palette. This will cycle only through the comps you have selected.