Have you tried to install skins before or recently? Might have affected the s4 items by mistake if you did. Try to uninstall and delete all InfinityMU files in your computer and re-install it to reset all the orignal files and data.
Yes I do understand buddy but have you tried to delete the InfinityMU client and completely uninstall all the files? You have to try that and re-install the game/client again.
Please try to download this file - http://www.mediafire.com/download/lj86w5mfe0f6hy5/. After downloading, extract all the files in your InfinityMU Client folder, run auto-updater, then run InfinityMU and let us know if it works.