unable to update ANY program

Can't find a fix.  Itunes can't connect, even with a working internet connection.  Windows update doesn't work.  AVGfree doesn't update unless I download the virus files off their website.  Malwarebytes can't update.  Either the connection times out or it says not connected  to the internet.  This has been going on for four weeks.  I can't figure out a solution.

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