How to change Google Drive for Windows Language to English

Before you start you should close Google Drive.
Then you need to go to Control Panel -> System -> Advanced System Settings -> Advanced -> Environment Variables.
Then on user variables press New button for Variable name enter LANG and for value enter en_US.
Restart the Google Drive and it should work now in English.

Reference: http://geektnt.com/how-to-change-language-in-google-drive-application-to-english.html