Layers window will not open... Help

When i open the window Tab and check the layers, it will not open. It shows a tick but now window opens, when i unchecked it it has a dash next to the layer title.

Window>Preferences>Workspace. Click on Reset Workspace and then try opening the Layer window.

Thank you worked!!! I am trying to do a model for a residential house and show the cut and fill on the earthworks, so not having layers driving me crazy! hard enough to work out how to model the earthworks!