When I type " nothing comes out, and if I type it again, 2 of it comes out as such: ""

Something is wrong with my keyboard : when I type ", nothing comes out, and if I type it again, 2 of them come out as such: "".

Same goes with the ' key. The first time I type it, nothing comes out, then if I hit it again two of them appear (so I have to backspace one of them everytime).

I've got no idea what I did to my computer, it was working properly yesterday. (I think I was messing around with the language thing, however I've just undid everything I've did and its still not working.)

There's nothing wrong with your keyboard at all. You've selected a keyboard layout that has dead key support on those keys. One such layout is US International, for example. Microsoft has a rather confusing table of all of the extra characters that you can type on your keyboard with these layouts. (It tells one the Unicode code points for the characters, but only hints at the actual key combinations to use to make them.)

Microsoft also provides the Microsoft Keyboard Layout Creator, for people to create their own customized layouts as they did in response to this SuperUser question, and some pictures of layouts.