How to install a language pack in VirtueMart?
Install the chosen language pack for Joomla! 3.x. Joomla! 3.x language packs can be downloaded from the official repository.
Then, upload the corresponding VirtueMart language pack files in:
administrator/components/com_virtuemart/languages.
VirtueMart language packs can be found at this URL.
Change the Joomla! 3.x’s default language from the Joomla! 3.x administrator area > Extensions > Language Manager. In this way, VirtueMart will use the new language by default.
Note that the language files for Joomla! 3.x and VirtueMart should have the same names. Alternatively, in Joomla! 1.5, the correct value for the backwardLang tag in the XML installer file of the language should be set.