The delete, sym and 0 keys don't work

[Exillium]

I've been using my Pearl 9105 since September last year.

The 0 key works if I press it repeatedly and I kinda have to press it hard.
While the sym and delete keys don't work at all, but sometimes they do, sometimes they don't, but of course mostly they don't work at all.

So what's this problem? Anything I can do to fix this?
It's been like this since 2 days ago, I don't know what I did. I never had this problem before.

Thanks