: Simply copying your profile folder (found in %APPDATA%\Mozilla\Firefox\Profiles\ ) to an external drive is the most reliable way to preserve your data.

While you can still find downloads for the Russian version, here is the context you should keep in mind:

: The creator stopped updating MozBackup in 2012. The Official Project Page explicitly states that the software is no longer being developed and may contain bugs when used with modern versions of Firefox or Thunderbird.

: For those who still wish to use it, the Mozilla Russia Utility page has historically hosted the Russian localization and installer.