Install Chinese language pack from Desktop Manager using the applications option after you download the latest multilanguage OS, and install to your PC.
On Desktop Manager (install it if you haven't), you should be able to update your phone. When you update it, make sure the Chinese Language Pack is selected. Go through the list properly to ensure what languages u want are installed.
EDIT: U need to ensure muti-language support OS is installd (as said above). U might be able to find it on blackberry.com
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