Mark --
Apply the View in which you want to see the missing column. Right-click on
the column header which is located where you want to see your hidden column,
then select "Insert Column..." from the shortcut menu. In the Insert Column
dialog box, select the Field Name of the column you wish to see, plus set
the Align Title, Align Date, and Width values to your desired selections.
Then click OK. For future reference, a hidden column cannot be "unhidden",
but must be "inserted" instead. Kind of confusing terminology, but
Microsoft Project does not work exactly like Excel. Hope this helps.