problem with unhiding

ok I was working on my model when I selected the helmet. I clicked to select the whole element, then clicked hide selected. I went to edit the underpart of the eye where the helmet was in the way. when I was done I could not unhide the helmet. I right clicked and selected unhide all but that does not work. the only way I know how to unhide parts of an element is to select another part of in and click unhide all. well I can not click on anypart of the helmet to unhide it. what should I do. I am stuck. I do not know what to do. I know it still exsists because I can see it in the render.