Windows 10: My lockscreen and wallpaper reverts back to default or black solid fill

My lock screen changes to default by itself after I restart my laptop. A similar thing has started happening now with wallpaper also. Even after setting wallpaper to an image, it reverts back to black solid fill by itself. I cannot figure out what is the problem. Kindly help

:)

 

Lockscreen Wallpaper is missing

After the recent update my pc is showing a black lockscreen instead of windows spotlight.... this problem is only when i select windows spotlight. If i select any other picture other than spotlight for lock screen then I am getting the wallpaper correctly,
but when i choose spotlight as lockscreen and sign in page it is not showing the image.

 

Lockscreen solid color, but with related search options still showing

A couple of days ago, and without my laptop having updated to my knowledge, I started getting a solid blue lockscreen. It changes when I change the color of my theme in settings as well. I do however, get the magnifying glass icons and search suggestions that are based on whatever the lockscreen is supposed to be for that day.

 

wallpaper keeps changing to black screen after shutdown

i recently purchased a microsoft surface pro 3 laptop, which runs on windows 10 pro. I started to realize that after i shut down my laptop and turn it back on, my wallpaper reverts to the default wallpaper. at first i thought it was due to a wallpaper clock
i downloaded from the internet, so i uninstalled it and deleted the default wallpaper. but now when i start up my computer, the wallpaper is just a solid black colour. how do i fix this? its so annoying having to go to personalize and reset my wallpaper everytime
i turn on my laptop.

also i highly doubt its due to any other programs, since the only thing in the computer is microsoft office