I have joomla 2.5.24 and I updated to VM 2.6.8. My main language is Hungarian, and in the checkout, in the billing informations gone english some text. So its mixed.
Are you using the latest hungarian language files from here?
http://virtuemart.net/community/translations
Currently, the hungarian language files are not 100 percent translated. A few lines are missing. If updating your hungarian language files doesn't help, you might consider to help with the translation here: https://www.transifex.com/signup/contributor/
No my site based on hungarian language. I never used language pack for VM somehow it was translated. But now something gone bad. I'll try your solution, and I'll write.
Okay, so I find the right language file in www/language/hu-HU/hu-HUvirtuemart.ini or something. So I have the translated file, but the VM don't use all the file or I don't know. Some text is in english some is in hungarian. Weird