I need to chage language from RU to EN but I can not do it.
Is it possible to do it without having to reinstall VS?
Hello. You can't install any language packs for the Visual Studio 2010.
You should make two steps:
Control Panel -> Region and language -> Administrative -> Change -> System Locale
Tools -> Options -> Environment -> International Settings
and change language to "Use Windows localization".
Read more information here
You can use Microsoft Language Interface Packs (LIPs) and Visual Studio. About LIP you can read here