Why can't I open any site to download anti virus software?

Please help.. i just can’t open any site..as in any antivirus softwares online..the page wont show it It shows the page as if im disconnected to the net. If I search others except antivirus..it loads.WaIs the Virus entered my pc blocking it?..How can I download anti virus and update it Ol if that so?… http://bit.ly/r8wOBy