Concentrate on one thing at a time. As it still boots, see if AVG will do a scan and say all is clear. Run webbrowser and remove any Browser helpers/toolbars that have been installed.
Then try getting ethernet cable connection to router working.
Is the router working correctly? Can you use any other devices on it. If not then try resetting it if you know how and have ISP login details/settings. If router is provided by the ISP then call their support line if the router is not connecting (look at the lights, are they as they should be?)
Everyone sitting comfortably? Ready to wet themselves laughing listen? Then we'll begin.
Last week, gormless me clicked on a phishing e-mail and nearly fell for it. I realised I could have downloaded all kinds of malicious stuff, so I downloaded AVG to deal with it. At that point my computer could still access the internet, which is how I could download it.
I set AVG to do a full scan, and rushed off to take the children to nursery and withdraw large amounts of money to tide me over until my new debit card arrived. When I came back, the scan had completed, loads of threats had been discovered, and the computer would no longer connect to the internet, either wirelessly on with an actual cable connected.
I've done the obvious stuff, like turning it on and off again, checking the hub, and finally uninstalling AVG. None of it has worked.