There are a large number of things he has not done.
For one, he never gave specific information about the machine he has. Or I missed it.
He can physically remove the Ethernet adapter from the machine. Then poser up without it. Then shut down and install a different make of Ethernet adapter. Install new drivers. Do the Newark wizard all over again. This should force Windows to do all settings over again.
He says he checked for malicious software. Did he? I said earlier that he should go to Super Dave in the virus section and go through the steps.
Newcomers forget, o never know., that AV software might catch about 80 percent of the stuff out there. The rest have to be caught by manual study of the logs of every bit of software that might have a unknown infection.
Another option is to restore his system to a date several days before this started.
Or, he could just re-install his entire OS. The would take less time than what he has spent on this thread.
If he can get to the site anyway, by using Linux, then there is not much point in trying to untangle this knot.I guess a co-student did a prank on him.