Default Language location

Hi,

A long time ago I loaded some software to modify the Russian keyboard on my PC. While it successfully modified the Russian keyboard, it looks like it also modified my language default and while most of the OS and error messages that I receive come up in English, once in a while I get them in Russian. I recently bought an HP printer, and its Solution Center screen is entirely in Russian. I know Russian but not the Russian technical vocabulary. Can anyone help me and tell me in which file the Default Language of my operating system is stored so that I could go and manually modify it back to English? BTW, my Default Language in the Language Settings of the Control Panel is fine (English). So I should modify it somewhere else.

Thanks!