User-1936818034 posted
Hi~ Notice the MasterPage is derived form UserControl but not Page class, so unfortunately there is no InitializeCulture() for it~ [;)]
One solution is as blows:
Let the user choose preferred language from your drop down. Once he chose one, store the value in Cookie or Profile, or any where you want.
Create a Global.asax, in Application_BeginRequest(), read culture setting from where you stored it, then set Thread.CurrentThread.CurrentUICulture and Thread.CurrentThread.CurrentCulture. This is because BeginRequest is touched off before the MasterPage's
lifecycle.
Additional, after user selected his culture, you should refresh that page to make it work. xD
There are already some discussion for your issue in
This Thread~