For example, US Keyboard and German Keyboard are different so if you set US Language for German keyboard some of the symbols will be misplaced.
To fix this go to: "Start"-"Control Panel" and under the "Clock Language and Region" click on "Change Keyboards and other input methods".Region and Language Window should appear and under "keyboards and languages" tab you can click change keyboards button.
Than click add language and make sure you set your language as default under default input language.
Also you can delete any other languages that you are not going to use.
After you set your language as default your keyboard will start working properly, you might want to restart your computer if you don't see any changes but usually it is not required.
