i am trying to edit a script in greasemonkey... but i chose a .ico file instead of a programa such as notepad... i cannot reverse it... do you have any clue as to what i should do?

It sounds to me like you're having problems with the editor that you've set to open user scripts. You can change this simply by opening about:config and filtering by greasemonkey.editor. Simply right click this value, and then set it to the location of your editor.