Event Viewer is a system file that is not easy to go missing. However, if someone has accidentally deleted it, it is best to repair the current Windows system image using the DISM Tool.

So the choices are to either monitor c windows\schedLgU.txt (moved to c windows\tasks\schedlgu.txt in Vista/2008), or write a bunch more errorhandling and a 'log to eventlog' function in your scripts.

If you see Event ID 55, 50, 140, or 98, The file system structure on the disk is corrupt and unusable in Event Viewer on Windows; follow this guide.