I need to block alt+shift keys event using C++, or some way to block changing language.
Thanks in advance.
I would go about it a bit differently. I would catch current langauge settings at startup than change it for desired one.
At the even of alt+shift i would just set it back to the desired type again.
It should be fairy easy to do with net framework.
Here is a short article about manipulating languages: How to change input language programmatically
And main class on msdna: InputLanguage documentation
To actually prevent alt+shift from moving into windows system you would have to play with hooks.
Here is an article about blocking keystrokes before windows process them.