Question: how to change keyboard language in windows 7 registry?
Answer: Start the registry editor (regedit.exe)
Move to HKEY_USERS\. DEFAULT\Keyboard Layout\Preload.
Double click on 1 and change the number to your local layout (you could get this by looking at HKEY_CURRENT_USER\Keyboard Layout\Preload1). ... 
You may also change HKEY_USERS\. ... 
Close the registry editor.
Logoff and then on again.