Laptop Keyboard settings got changed while using External Keyboard.

Friends,

I have a Lenovo 410 Laptop. Recently i bought an external Lenovo Keyboard (wireless).While using ext. keyboard, laptop keyboard settings got changed (if i press one letter, it would type another).is there any way to understand that how it would have got changed. It would be of a great help if you can guide me.Because of this problem i am not able to login.