MacBook External Keyboard

Hi I have a problem with the external Apple keyboard I bought for my macbook. I disconnected the internal keyboard because my shift key was always pressed and apparently there is no fix for that (tried everything, literally). So I plugged in my external keyboard and now the only keys that seem to work are the volume controls and the caps lock lights on when I press it. Could it have something to do with the internal keyboard being disconnected? I really need to use my laptop because I have a bunch of school work to write and now I'm going bananas because of this. Maybe I could somehow reconnect my internal keyboard and disable it? I don't think there is any malfunction with the ext keyboard itself because I've plugged it to my ps3 and this is how I was able to post this. Any help would be kindly appreciated. Thanks.