Touchpad replacement and keyboard issue.

My touchpad is not working properly its like the mouse button is always clicked when i turn on the touchpad.so i want to replace it so how much does it cost?

And some keyboard button have problem like my number 2 button doesn't work but it works when i press it with any button pressed along with it - if i keep caps-lock and press 2 it does give 2 like that if i press shift and press 2 it gives the '@' symbol. So the key doesn't work if it is pressed alone but works when multiple key is pressed.