From BlenderWiki
Supporting Status
Garlic supports 24 languages for now, which are as follows( you can find a .Blanguages under /bin/ which contains this ):
English:en_US Japanese:ja_JP Dutch:nl_NL Italian:it_IT German:de_DE Finnish:fi_FI Swedish:sv_SE French:fr_FR Spanish:es_ES Catalan:ca_ES Czech:cs_CZ Brazilian Portuguese:pt_BR Simplified Chinese:zh_CN Traditional Chinese:zh_TW Russian:ru_RU Croatian:hr_HR Serbian:sr_RS Ukrainian:uk_UA Polish:pl_PL Romanian:ro_RO Arabic:ar_SA Bulgarian:bg_BG Greek:el_GR Korean:ko_KR
There are about 7000 items in the translation files, and most languages have not been finished, yet. So sometimes you'll find not-translated string in the UI.
When new items added by developers, there will also be some delay before translators fill the translations, and everyone is very welcomed to help Blender translate it in time. See Notes for Translators for more information.
Preperation
Firstly, your target language must be in the list. If you want to add another language, please see the Notes for Translators's "Add New Language" section.
Next you should make sure that the target locale has been installed in your system. You can think it as a language package. For example, the following command under Linux will list all available locales:
locale -aIf the locale is not installed, you may get a warning message "You cannot change to XXX nor XXX.UTF-8" in command line, and nothing will change in the UI.
Switch Language
When all preparations done, select File->User Preference->System, you can see "Select Language" options. Select the target language, or select the Default to use the system settings.
Then save your settings and restart Blender. You'll see what you want if nothing is wrong.
If unfortunately something goes wrong, such as displaying "You cannot change to XXX nor XXX.UTF-8" in the shell, you may havn't installed that locale. See the "Preparation" section again. If it is still unclear, please email me at xiaoxiangquan AT gmail.com, or turn to the Community Support Forum for help.
Back to English
If you are not used to the locallized Blender, just switch the language back to English following the upper steps.
FAQ
Q:How do I change my language?
A:Select an item in File->User Preference->System->Select Language, and restart Blender.
Q:Why does it say locale missing?
A:Maybe you haven't installed that locale. See the Preparation section for details.
Q:why doesn't it change when I've selected one language?
A:Check if you have installed the target locale. See the Preparation section for details. If still unclear, please email me at xiaoxiangquan AT gmail.com, or turn to the Community Support Forum for help.
Q:Why the translations are incomplete?
A:See the Supporting Status section. For now, only Simplified Chinese is always keeping up to date with Garlic. Others are somewhat incompleted.
Q:How to change font?
A:We only use unifont. Maybe users will be allowed to select a font in the future, but now if you want to change, the only way is to edit the unifont's TTF under blender's DATAFILES folder.
