Question

I’m developing a website where the language is different from English. Is it possible to change keyboard input language to a certain language when the active window/page is the website?

Answer 1

No. It is not possible to change the keyboard input language from a web site.

You can suggest that a user use a particular language, but you can’t control what they use.

You could detect the user language by inspecting the Server variables

var language = Request.ServerVariables["HTTP_ACCEPT_LANGUAGE"];
var charset = Request.ServerVariables["HTTP_ACCEPT_CHARSET"];