Worked like a charm. The other gave me bsod and had to refresh.. Thanks Guess I missed it somewhere, we don't have "Thanks" button anymore?
I've tried reverting, running as admin and reverting, looking for other ways to change the lock screen wallpaper and nothing has worked yet. If I find something I'll let you know.
Can you delete C:\Windows\Web\Screen\img100.jpg and rename C:\Windows\Web\Screen\img100.jpg.bak to C:\Windows\Web\Screen\img100.jpg ?
This worked. Thank you so much! I needed to restart first before it would change. If you need any more information, let me know.