How to install new language if that option is blocked?

I bought tablet in providers's shop, so it had some applications preinstalled, and also some of functions blocked. My Android 4.1.1 has no option to install new language in "Android keyboard". I have another keyboard installed in my mother language, and it works fine, but I bought usb keyboard which recognize only Android keyboard, so some characters in my languages don't work. I want to know is any possibility to add new language in some other way (I don't want root until garantee is over), OR maybe there is some application which can do to me to can manage with usb keyboard to recognize that another keyboard in my language. I hope u'll understend the problem and someone will help me.

Tnx, I installed "External Keyboard Helper" and solved my problem.