Did you delete or send the file to Chest?
If you really deleted… well, no solution besides trying overinstallation.
Just choose ‘Repair’ installation of Windows and install ‘over’ the old installation.

http://support.microsoft.com/default.aspx?scid=kb;EN-US;315341
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q314058
http://support.microsoft.com/?scid=kb%3Ben-us%3B315341&x=15&y=0
http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/tips/doug92.mspx