Not sure you can recover but there is a great lesson in your pain nonetheless. Get in the habit of saving you image every time you make a change and then track that change in the save file. For example, my process file includes images with names like M63_Red_DCrop_DBE_MLTNR_HT, for example, which helps in two ways. First, you have everything but the last step saved. Also, you have a ready place to go back to if you want to tweak noise reduction without having to start all over.
Hope that helps.
Jim