There is a bug in the computer but I can't identify it - Virus, Trojan ... - BleepingComputer

I have been running Windows 7 and want to update to Windows 10.  In December I was researching a topic in Japanese history, did a Google search, and was looking at some of the sites that turned up.  I got to one that looked quite innocent and possibly useful, clicked on it, and got a porno site.  I immediately went to shut it, but before I could do so the computer was shut down.  Things started to go wrong in the next few days.  I was trying to contact MS Support for guidance in backing up my files before changing the OS, got a helpful agent who was suppsosed to email me contact info.  No email from him ever arrived.  I had a number of other things impinge on my life, and by the time I got the external hard drive I was pretty much out of commission for two weeks.  Meanwhile I was plagued by bluescreens and other buggerups, to the point where I could operate only in Safe Mode.  I had moved to Office 365, but got a message that I had to download ClassicMenu for it (why? it should have worked from the ribbon), then a message that Office was not properly installed.  I uninstalled it and tried to reinstall (I had to do this several time with Office 2013), and was unable to reinstall.  So now I have no Office.  This morning I went back to MS Support, tried to follow a procedure posted by MS Community and found that their instructions were useless, finally got an agent, and he simply didn't want to deal with it.  I have run MS Safety Scan full scan a number of times, and several other scans, and they turn up nothing except occasionally some trivial PUPs.  But I am now thinking that perhaps my best bet would be to try to identify and remove the trojan or whatever it is.  I am pretty certain that the Japanese site planted something truly nasty.  If I can regain normal function of the computer, the OS upgrade should be a good deal simpler. 

So this is where I now am.