Herenvardo - 9:47 am on May 17, 2006 (gmt 0) Hoping be useful,
Since the times of Office 97, most of MS' products' toolbars and menu bars are 100% customizable; and MSWD2005 express isn't an exception.
Simply go to Tools/Customize... then go to the tab Commands and search for the command you lost. Once you have it, you may drag it to wherever you wish.
Alternatively, also from the Tools/Customize dialog, you may go to the Toolbars tab, select Menu Bar and then click Reset... it will ask for confirmation and then restore the main menu to the original configuration. Guess this will be easier than doing a system restore and this stuff, which could cause duplicated program files and loss of hard disk space.
Hoping be useful,