NFO files are typically text files that store information about pirated software, but they can also store Microsoft system information, saved Age of Empires player information or data files for the Folio Views infobase product. These types of files can be difficult to open by double-clicking them. Windows by default tries to open these files as system or help files. You should be able to open them using a text editor.
Locate the NFO file you want to open.
Right-click the file, and a menu will appear.
Click the "Open with" option. Move the mouse to the right and select the "Notepad" program. Notepad will open the file and allow you to see all of the text contained in the NFO file.