Editing the PAR file with notepad

[lowglow]

Hi
I would like to know how to edit the par file with note pad.I opened a par file useing not pad and then when I closed note pad the par file icon has been changed to the note pad icon and now when you click on it. it opens with note pad, also every other par file for every plane I have on my PC has changed aswell, how do I change them back?