Virus preventing internet access


Recently i downloaded something form the internet which infected my system.
Now i cant access internet coz of the virus,trojan or a malware.
all the antivirus software like Norton, spybot search &destroy, a-squared
and adware which i have were not updated and now i cant update them coz no
internet access,
I tried running each one antivirus software from safe mode but i still cant
access th the internet.
It gives me weird message when i try to access the C drive by clicking on it
but when i right click and select explore i can access the C drive

Can anyone please suggest how i can get rid of this problem
i would appreciate any response