I allready told you and also asked you this very thing.
As you have another language set, you NEED to add a folder and name it the very same as your own language in
Themes/default/languages/ you see the english folder themre, Inside that folder, you have ALL the images needed.
you need to add a folder there,
Themes/Default/languages/ YOUR LANGUAGE/ and then copy all the images from the english folder into that new folder,
If your custom theme holds images for engligh, you will have to add it the same way in that themes language folder to.
Themes/YOUR THEME/langauges/( add folder and name ti to your language )YOUR LANGUAGE/copy images from englishfolder into this new (your language) folder
For more info on how to work with custom languages to your forum, please visit and read the documentation on simplemachines,org