Need helP

Is your function key stuck? That is, maybe the keys are working, but they aren't doing what you think you are telling them to do.  

I know on my laptop, left and right arrow are up and down volume if function key is stuck. I wouldn't notice though, as I don't use the internal speakers.

Other than that, it would be unusual to have both left and right arrow keys die, but no other keys affected. If you've dropped the laptop recently, there could be a loose ribbon cable somewhere. But I would think that would affect more than a couple of keys.