Robert got bit by a phishing scam about being a workshop presenter. He clicked on a link to download an attachment and nothing happened. He realized what he had done and disconnected his desktop. Now he thinks he needs to reinstall? Leo says Nuke from orbit. Do not install from in-place. He should want to back up data, wipe the hard drive, and then reinstall Windows from a known, good source. But he should make sure to know if he actually has malware. If he has a WInMail.dat file attachment, that's from Microsoft and older Outlooks use it.
Run MRT and Windows Defender. If Robert ends up with nothing, he should be fine.