Whenever i try to access any antivirus website.. the page doesnt open ..?

i have to download software from third party vendors ... this all started while emsisoft software Purchased Edition.. uninstalled it, reinstalled norton - nogo, AVG doesnt install - asking me for my proxy settings .. which i am not using .. the reason i had to remove emsisoft cuz it was not updating .. & website was not opening too ... btw any antivirus website incld. malware byte, norton, emsisoft nod32 etc . etc .. plz tell me what to do.. i dont want to reinstall OS .. i have scanned by sys complete with malware bytes still nogo