Computer Guru Types

I’m stymied here. I wondered if any of you have any ideas.
The boys computer crashed. I restored it and got online. I could connect to Gmail and Google, but could not reach Norton or a couple of other websites.
I tried to go to You Tube and was told that I needed Internet Explorer 8, which I downloaded. I also downloaded some automatic updates.
When I reboot, I could not get online at all. I get the Explorer cannot find website error page.
I was not sure Internet Explorer 8 downloaded correctly, because of the connection errors I got earlier, so I copied the files from the Program Files/Internet Explorer folders from a working computer and moved them to the wounded computer.

No luck.
Not sure what else to do/try. Any suggestions?
Much gratitude!