Fair warning - I'm going to be irritated with you.
There are 3 or 4 major vendors (depending on how you count them), and dozens of smaller vendors in this (anti-virus) marketplace. You've provided ZERO information on your O/S, your brand, style and version of anti-virus, and you expect us to somehow magically come up with an answer for you.
Have you bothered to read the instructions that came with it?
seriously, we are not the psychic tech support network. What we (as a group) are able to do, is to shed some light on a problem when we're given background information, and we can match that to each of our personal experience in this business.
Every manufacturer has their own commands, options, etc. - and changes those through time, as they learn what works.
When you said "without using any virus scan tools", that pretty much eliminates what most of us do or use.
Is is possible that you meant "No GUI tools" ?
In complete fairness, I'm not just picking on you, but on all the people who throw vague, hopeful questions on this forum - somehow hoping that we (as a group) will figure out what you really meant, and provide a step-by-step solution. I'm sorry, but much as we like to help, we can't. We've got to have more information to go on than "it's broke".
It is not actually possible to scan your computer system manually for viruses or any malicious programs installed. You still need to use a third party software tools like antivirus or antimalware programs. Make sure that you use an effective and latest antivirus software for your computer security.
You are referring to manually scan potential viruses to your computer system. It is actually hard to do this stuff because it is too complex. You don't need to make the situation more complicated, just an antivirus software and scan your computer system.