My older sister blocked a website on my computer how to unblock it?

she was only joking she blocked hotmail cos she sed i read my messages often she sed she wud remove it but
yesterday she went to turkey and she forgot. she will be their for 3 months and i have important stuff in my messages
i have google chrome i click on the website and it says "Web Site Blocked By BSkyB Firewall"

how can i unblock it?

It would depend if it is blocked through the use of software or blocked at the router itself.