Photos Recovered But Cannot be Viewed

I am using Windows 8.1

I am trying to recovered images that I deleted from WD external hard drive.

I was able to recover all of the images I needed (only about 30), but when I open them, it says the image is not supported.

The file types are .png and they're small images (about 200KB each).

All the thumbnails are the stock window images of a regular yellow sunflower and a red sunflower instead of thumbnails of the actual photos.

I am confused as to why I can't view the images. The sizes (as in KB) of the images all seem to be correct.

I was able to recover and view other photos I deleted at the same time that are much bigger but where in a different folder.

I did put in new things into my hard drive; about 6GB worth, however, I have about 150GB free on my hard drive. I didn't expect the deleted files to be overwritten already.

I really want those photos back. Can anyone help me out?