Connection time-out has occurred... :(

I am using a Macbook (2009 version) with OS 10.8.3, and have just come home for the Easter holidays to my parents' house where I have always automatically been connected to the wi-fi. They have not changed or moved anything to do with the wi-fi box, but for some reason my Macbook isn't automatically connecting, and I can't manually do it either - as soon as I try manually a message pops up saying 'Could not join [Network Name]. A connection time-out has occurred.' I have tried turning the Macbook on/off/restarting it etc. and the same with AirPort, I have restarted the wi-fi box and left it for minutes etc. but nothing is working.

I really need internet on my Macbook ASAP as I need to submit some work by the weekend and it is all on my Macbook.

If anyone has any suggestions of what I should try I would be very grateful as I am desperate to get my wi-fi working again.