Thanks for your help dear @Diana,
Please note that I want my website users see all of content in translated language. When I change "Site Language" to "English" (Setting>General>Site Language), Everything became English, but I want just the admin panel language became English not the whole content of site .
You can check again. I Deactivate the plugin that you tell me about it but, when the "Site Language" became to localized language, most of items on LMS menu didn't appear in english.
Please see this :
link