I'm having trouble with my keyboard. I think it happened when I installed the keyboard but some symbols type different to what's on the key. Can you help?

You have prob hit the num key. It is located top right of keyboard, it should say num on it or num lock. Press it once and hopefully your problem sorted

Could also be the keyboard itself is going bad. When you say it is showing different stuff, can you give me an example as to what you mean?