>>8 I had to do that a couple of times due to not knowing much code. The first virus was from an add and messed with the boot code. It just stayed on a black screen with the underscore blinking at me every time I booted. That is why I use adblock plus now too.
The other is when the system files became corrupt. I didn't think much of it till I needed system updates and I couldn't due to the system files missing, or being altered, after the virus was removed. I tried everything to fix that one, but nothing really worked on fixing those system files.
If I knew more about programming, and the code in win7, I might have been able to fix some of the problems without resorting to the system backup.
But the OP is asking how to manually remove a virus without the use of a program. A system backup utility, to my knowledge, is a program.
So it seems
>>9 does in fact know more than
>>8, since 8 didn't even answer any part of the OP's question. While
>>9 did offer insight into the original question asked.