As you know, Photoshop Elements doesn't support layer groups. If you happen to work with files created in full Photoshop, you can neither see nor select grouped files.
The following two actions let you edit such a document.
- Select a layer group in the Layers palette.
- Double-click the "Ungroup Current Set" thumbnail in the Effects palette.
- Edit the ungrouped layers individually.
- If necessary, group the layers again.
To get rid of all the groups in a complex document, apply the "Ungroup All Layers" effect.