A button on my samsung wave has broken. It's the middle button that gets the menu screen up. If you press it it just doesn't work

I have this phone on contract and I only got in September 2010 so have 18 months left on it!

Never had a contract phone before. What can I do? It's with Virgin mobile. If I took it to a shop could they fix it? replace it?

Sorry if I sound thick but really need some advice if something like this has happened to you.

THANKS