If you do a file|print preview, can you see it?
If yes, then maybe (from the worksheet menubar):
Window|arrange|tiled
then resize that window the way you like it.
If no, then maybe it's not opening. When you clicked on Window, did you see its
name at the bottom of the dropdown?
Or maybe it's opening, but hidden.
Click on Window
Is Unhide enabled?
If yes, unhide the workbook and save it so that it's ok for the next time.