thumbnail are flipped

[namarang]

I guess you mean thumbnail instead of icon. Digital cameras store EXIF information on the image files. It includes the orientation of the camera when the picture was taken (landscape? or portrait turned to the right/left?). Many image viewers read that orientation field and automatilly turn the image for you to appreciate it, so you don't have to tilt your head to the left/right. Windows Explorer is showing you a miniature with the original position of the image, while the image viewer is showing you a temporary "corrected" visualization. You could open your image viewer settings and disable the option to do that, but you will see the image tilted. You would have to use an option to permanently rotate the image. Read your image viewer's help in order to see how doing that would impact on the quality and EXIF information of the original image; you could also rotate and save as a copy, and then compare both files.