Hi:

Have you determined that notepad.exe is actually missing by doing a search for it (Start>Search>Files and folders, and
type in notepad.exe)? If not, you might just be missing the desktop shortcut. Usually you can find it in your C\Windows folder,
or by clicking Start>Programs>Accessories. When you find it, right-click on it and select Send to>desktop (create shortcut).

Note that your question involves software, not hard drives, and any further questions should be posted in the software board
corresponding to your operating system:
http://forums.us.dell.com/supportforums?category.id=software