Z and Y keys are switched in N5110

Hi

I have N5110 and a very weird problem when I type. Whenever I press the letter Z the laptop recognizes it and shows it like Y and vice versa. The problem is limited to these two letters only. At first it began in Word, now its applicable to the entire laptop. I checked language and input settings everything is in order.
I don't know what to do, or how to reinstal the driver for the keyboard. please help!