Windows 7: File Associations?

I was recently downloading a minecraft custom map when i messed up and opened with wordpad and changed how my files are saved i am sort of a noob with file associations and i am not understanding how to reset the windows 7 defaults i have read numerous threads and i don't understand. I do not want to install special programs to open these files i just need the default settings.

Give this a shot: Default File Type Associations - Restore

-Justin