I've someone posting on here, Tony, with difficulties in getting their computer to connect to the internet. It was a classic problem that I've fixed for people many times before, by simply providing them with instructions on how to reset the TCP/IP stack. (It's dead easy and takes less than a minute to do).
Before they'd seen my reply though they'd taken their computer to PC World, who did a clean install of Windows (thus deleting all the documents, photos, videos, emails and software on it) and charged them sixty quid for effectively wrecking their computer. (PC World's standard 'fix', for anything they can't instantly diagnose, seems to be to reinstall Windows. That should always be the LAST resort, not the FIRST one!)