My MacBook keyboard stopped working.. how can I fix it?

days ago, my 13" macbook started having problems. first, the highlights on a folder wouldn't go away, no matter what other folders i clicked. whenever i needed to preview pictures from a folder, it would always show the bottom half of the contents. when i had to shut down, the laptop would make these ding sounds continuously. when i tried logging in to my email account, it would show one letter filling the username field on and on. and now, the keyboard doesn't work at all.