Hmmm... I have an idea, but am not sure if it'd help you. I remember that sometimes for some reason on keyboard 'round here the row of '~' until '=' somehow changes, so when you use Shift + a number key it doesn't display the proper thing.
Now, when I change the keyboard setting or language setting (to English, US, or something like that), it changes back to normal. So that's why I think you just try to change the settings of your keyboard/language and see what happens. It's just a wild guess, but maybe you're lucky? G'luck!