If you have only 2 languages on Windows to switch, you can use Ctrl+Shift or Alt+Shift to switch between them.
But if the count of languages is more than 2 (I have 4), it becomes tricky to use the same key shortcut to switch them in round manner. Also, there is an option to assign separate shortcuts for each language (for example, Ctrl+Alt+1, Ctrl+Alt+2 and etc.), but this solution is tricky too, because you have to use both hands to switch the language.
What I need is a way to assign one key for one language. My keyboard has a few keys which I don't use (those keys like 'Open browser', 'Open mail', 'Print' and etc.). How can I assign them for switching languages?