Windows 10: Thumbnail preview never appeared before, resolution, etc.

Thanks for your help in advance!
Here are my problems.

I unplugged my external monitor for a couple of hours and this happened:

1. I cannot adjust screen resolution back to 1600 x 900
2. Whenever I type, hitting the backspace key till the area to erase just sits still until I hit it one space at a time.
3. I am now seeing the thumbnail previews when my mouse moves over the program that is in the taskbar - I never saw this before.

Normally, I can fix things like this on my own, but, seeing that it is Windows 10, I'm still learning it.

And, is there a way to disable the thumbnail preview without changing the registry? I've been searching online and every site that I find tells me to do so.

Can someone help me please! It is interrupting my work because I cannot concentrate, plus, not being able to erase a sentence or even a couple of words is giving me a headache - literally.

Thanks so much!

:)

 

Windows 10 File Explorer video thumbnail display problem

I've just upgraded from windows 7 to windows 10 and am now on build 10240.

In file explorer, I open a folder that contains pictures; I select one and the picture thumbnail appears in the preview pane. I select another picture and that thumbnail appears in the preview pane - that all works as expected. Now, I open a folder containing
videos and select one (say video1). The thumbnail appears in the preview pane and is playable from there. Now I select another video (say video2) from the same folder but the thumbnail from video1 still remains in the preview pane. If I double click the thumbnail
in the preview pane it now plays video2 ! Even if I switch to a different folder that contains other videos, the same thumbnail (video1) remains in the preview pane although the correct, selected video would play if the thumbnail was clicked.

I thought maybe my thumbnail Dbs might have become corrupted so I deleted all of them and let Windows rebuild them. Problem remained.

Any ideas ?

 

This file does not have a program associated with it for performing this action. Locked out of folders!

I had those problems with video files and the thumbnail was just blank. I renamed the file with the extension .mp4 and the thumbnail appeared.

If it's a text file put .txt at the end of the file name, etc. I never had that problem with a folder though.