WordPad is a program of the Windows operating system that's used to edit and format text files. It is possible to delete the program from the operating system, and it is a common mistake people make when doing a thorough clean-up of their computer. It is possible, however, to reinstall the program, should it accidentally be deleted.
Go to the "Start" menu, and open or expand the "Control Panel." Open the control panel for "Folder Options." On the "View" tab, under "Advanced Settings," check "Show hidden files and folders," and uncheck "Hide protected operating system files [recommended]." Also uncheck "Hide extensions for known file types."
Open Windows Explorer from the "Start" menu. It will be located in "All Programs," and may be in the "Accessories" folder.
In Windows Explorer, navigate to %systemroot%\inf. This is the folder named "inf" that is contained in the folder of your operating system. For example: C:\WINDOWS\inf.
Locate the file named "wordpad.inf." Right-click on the file, and select "Install." You should now be able to access WordPad again.