There is no lost items 'editor'; the post describes a procedure to temporarily swap files in your saved game folder (which keep track of your inventory) with a set containing a required item. After loading the save with that and dropping the item on the ground, you need to save again and restore your original set of inventory files. Make sure you save under a new name before attempting this.
Are you familiar with file management type stuff (moving/copying files or folders) using Windows Explorer, or can you get someone to give you a hand?
Check your PM (click '
My Home' in the top menu bar, then 'Received Private Messages').
