Problem with Wallpaper

[Stephen P. Molnar]

I am running Buster/XFCE4 Desktop  on an LG Model24EN33 LED Monitor. 
This morning, after being shut down over night , when I turned on the 
monitor it came up with the black wallpaper that I favor. After closing 
an application the portion of the screen that was covered was a light gray.

Changing the wallpaper did not change the appearance of the screen.
I don't have the faintest idea as to what is going on.

Help.

Thanks in advance.

--
Stephen P. Molnar, Ph.D.
www.molecular-modeling.net
614.312.7528 (c)
Skype:  smolnar1