Editing an image to photoshop and remain the layer untouched. how ? and what tool is it?

You Question is not Clear.

Anyway one answer is: Using a Masking in a layer u can edit a image in Photoshop and leaving the Image in a layer untouched.

Just as Shinu stated, Masking is the best way to edit an image without touching the original layer. Duplicating that layer and masking it is also the way to go around with it.