Lost images in my cloud folder

I have a my cloud 3tb.
I back up from my iPhone to a folder called backup on my windows 7 pc.
Last night was copying images out of it and placing it in to necessary folders when all pictures in the back up folder disappeared .
The folder had over 800 images and was only copying a few at a time .
I have checked all my folders for the lost images also the reyclying bin.
Any idea ?

I am a bit confused by your post. If you were copying your files as opposed to moving them then the original files should still be in the original Windows location.