A. The ID for the current language is stored in the registry value HKEY_CURRENT_USER\Control Panel\Desktop\MultiUILanguageId. When you request a change to the language, the ID for the new language is stored in HKEY_CURRENT_USER\Control Panel\Desktop\MUILanguagePending and takes effect at the next logon. Both registry values store a number that corresponds to the language ID you've chosen. The table below lists the available value.

Language Name Language ID
English (default) 0409
French 040c
Spanish 0c0a
Italian 0410
Swedish 041D
Dutch 0413
Brazilian 0416
Finnish 040b
Norwegian 0414
Danish 0406
Hungarian 040e
Polish 0415
Russian 0419
Czech 0405
Greek 0408
Portuguese 0816
Turkish 041f
Japanese 0411
Korean 0412
German 0407
Chinese (Simplified) 0804
Chinese (Traditional) 0404
Arabic 0401
Hebrew 040d

If you request a language change, then want to cancel the change, you can open a registry editor and change the MUILanguagePending value to that of the MultiLanguageId value.