I set all my yml folder to open with notepad on Minecraft Server?

Is there a way to change them back, because it broke the server.

Added (1). I mean that EVERY yml folder on my computer is set to always open with notepad, and i need to a way to change them back to yml.

No, unless you got a backup. You shouldnt use notepad, download Notepad++, its free and better. You must configure it to "replace tabs with spaces." In Notepad++, this can be changed in Settings > Preferences > Language Menu.

Furthermore, YML is really. Not unstable, but crashes a lot. With that i mean, one space too much or less, and a whole plugin could fail. For the first days, before saving your yml file, copy and paste EVERYTHING here: http://yaml-online-parser.appspot.com/

If there's an error, it will be red, and it will say what the error is.