first, we need to know that a new encrypted virus can be undetectable to all or some of antiviruses,its just a question of time for the virus to be detectable,that's why antiviruses need always an update.
scanning with more than 40 antivirus will just increase the chances to detect virus, and of course never it will be 100%.

use these websites to scan your files online for viruses.
https://www.virustotal.com/
http://virusscan.jotti.org/

threatexpert scan your files and give you good additional information about who hacked you, ex his(email, no-ip, domaine name,irc channel...), specially the viruses that takes control  of computer or steal informations.
http://www.threatexpert.com/filescan.aspx