Display Language Switcher is a mostly automated script to install and change the Display Language for Windows Editions that are not allowed to have multiple languages by default.

Some of these editions include Windows 10 Home Single Language, Windows 8.1 Single Language, Windows 8 Single Language, Windows 7 SP1 Starter, Windows 7 SP1 Starter N, Windows 7 SP1 Home Basic, Windows 7 SP1 Home Basic N, Windows 7 SP1 Home Premium, Windows 7 SP1 Home Premium N, Windows 7 SP1 Professional, and Windows 7 SP1 Professional N.

The following languages are supported: Arabic, Bulgarian, Chinese (Simplified), Chinese (Hong Kong S.A.R.), Chinese (Taiwan), Croatian, Czech, Danish, Dutch, English, English (United Kingdom), Estonian, Finnish, French, French (Canada), German, Greek, Hungarian, Italian, Japanese, Korean, Latvian, Lithuanian, Norwegian, Polish, Portuguese (Brazil), Portuguese (Portugal), Romanian, Russian, Serbian (Latin), Slovak, Slovenian, Spanish, Spanish (Mexico), Swedish, Thai, Turkish, and Ukrainian.

How to use:

1: Get desired Language Pack matching your operating system version and architecture (32bit or 64 bit) and put the file in "LangPack" folder. For Windows 7, you can use the original EXE file, or manually converted CAB file
Optional: Get Language Features On Demand Packs for Windows 10 if available and put the files in "FOD" folder
you can let Windows Update to install them later after changing the language
2: Right-click on DisplayLanguageSwitcher.cmd and select Run as administrator
3: After loading and showing Operating System and detected Language Pack information, you will be prompted to continue to install a new LangPack or exit.
4: Restart the system to complete the language change

A few notes:

If you later want to go back to the original language or already installed multiple languages run the script, and you will be prompted to select one of the detected languages to set as primary

The script will not set or change the local language preferences: Formats, Location, Keyboards, language for non-Unicode programs (system locale). You can set them manually, before or after changing the display language:

Windows 7: "Region and Language" Control Panel Windows.
8/8.1: "Region", "Language" Control Panel.
Windows 10: "Region," "Language," Control Panels, or Settings app.