Use system restore. Some viruses disable this feature. If that is the case, shut down and restart in “safe mode.” Try safe mode with networking first and restore there. I have had to restart in safe mode with command prompt. When the computer boots you will get a command prompt like in DOS. At the prompt type rstrui.exe Some of my computers use different F keys to reach “safe mode”, one uses F4 during startup, another uses F8. Hold the key down while the computer is booting. My office staff like to surf the internet, and I have had to deal with several viruses. This has always (well, almost always) worked.
I’ve used the sytem you discribed two or three times.
It’s almost a perfect fix. Pick a restore point as far back as you can, and whem everything is running again install virus protection pronto