Which version of Photoshop are you using? Where are you searching for a content-aware cop tool? Would you mind sharing what you do with this tool? It's available in Photoshop. What do you mean by disappeared?
It could be hidden inside of a group of tools or it could have been removed from the toolbar and is now a hidden tool. Go to Edit > Toolbars. Choose "Restore Defaults" to return all the tools to their default locations.