I am now trying to undo what happened with the bulk restore, I would suggest what has happened involves both images with custom thumbnail sizes and the conversion of PNG images to JPG format to optimise them but the image links within my posts still point to the PNG. Whatever the cause this is not something I want to have to get my head around, having spent a day letting it run I am now spending a day trying to undo the process without knowing if it will work or not.
