Thx Brink for the .reg file. Now everything gone back to normal default "unknown app" again. Thx you so much :)

Its default program = unknown application. So i want to change back it from notepad to unknown application again but from the "Open with" list there's no unknown application to set as default. So......

I have a request for .json file type. I mistakenly open it with notepad + checked the always use this app to open .json files :( and now i want it back to default. Can you help me with this? Thx b4...