Depending on your laptop, you can take out the keys, clean them and reseat them and they'll sometimes work.
However, you may also have one of those membranes under your keys, when they get moved slightly, you'll hit one key but it'll type on another. So you can take apart the keyboard, move the membrane around back to it's correct locations, then put it back together again.
It could also be that you've spilled something on your keyboard, even a small amount of water will cause shorts in the keyboard. One cagain, you'll have to take it all apart, clean it, and put it back together to fix it.
Then again, you may have a loose ribbon cable from your keyboard to your motherboard. You'll still have to take the laptop apart to fix it.
So, you can try fixing it yourself by taking the laptop apart, or you can take it to a repair shop and let them do it.
Unless you're running some sort of weird macro program. If so, stop it and see if that fixes it.