Hello Haydar Ghafoor,
Thanks for coming back to share the fix. That Folder Options toggle exists for performance and policy scenarios where Explorer is told to render generic icons only and skip thumbnail generation entirely, which is why the picture folder looked blank of previews until the box was unchecked. Once it is off, Explorer resumes building thumbnails from the image cache and the change applies across all picture folders without a reboot.
Information like this are useful because the same setting can get flipped by certain OEM configurations, group policies, or storage cleanup utilities without the user being aware, so a clear write-up of the symptom and the exact toggle helps the next person searching for it. I appreciate you sharing the resolution.