What do you mean by "missing one" and "renaming". What did you do step by step to fix it? Do you need any special tools?
When the game says it fails to load image, you can see the path of that image. Go to the files, there you copy file that have almost the exact name and rename it just how the game is showing you that you don´t have. Just renameing of similar file can lead to problem of not having picture with that name.
There are files that game says have name for example "Cowgirl%20yellow" you name that file like this "Cowgirl yellow".
Hope it helps, sorry if I am not making sense, this is not my first language.