I take it you mean that the keys on your Sony notebook (and not the external keyboard) no longer work properly?
It sounds like the numpad function of your notebook's keyboard is on, or stuck on for some reason. Usually these keys are activated by the function key (fn), but you have to hold the fn key down to get them. Perhaps your fn key is stuck? and have you tried restarting the computer - often that can work wonders. If it doesn't, it might be that the external keyboard has caused issues with your built-in keypad's drivers/software, which might be not so easy to try and fix.