I want to know if there is a way to change the Lock Screen in Windows 8 without using the default PC Setting way. Maybe a value in the registry or something?
You can try replacing the picture in C:\Windows\Web\Screen with your picture to see if its works. It must be called
Windows 8 Apps can ask for permission to change the lock screen. One such app is called Bing My Lockscreen and pulls down images from Bing's background pictures library. This doesn't let you set a specific image, but gives you some choices to choose from.
If you need a way to this programatically yourself, you could write your own app for it. There is documentation on MSDN for Lock Screen Personalization.
Alternatively, you can manually edit the lockscreen background image. It appears that this is stored per-user in
Update: I tried messing around with the above registry settings, and was unable to change anything. I actually managed to break the lock screen by deleting an entry, so... don't try that at home!
Some folks in this TechNet forum thread were able to automate this by writing a script to overwrite the default backgrounds, which are cached in a hidden folder. Merely changing the folders mentioned above doesn't work. Depending on why you need to do this, there may be a solution in there.