W64.Viknok.B!inf is a stubborn Trojan virus. You need to remove all its files and registry keys from your PC.
To find show hidden files, you can Open Start Menu and then go to Control Panel. Then use the search bar to look for Folder Option. Check Show hidden files and folders and un-check Hide protected operating system files (Recommended) in the View tab of Folder Option window.
If you don't mind, I can recommend a removal guide that contains detailed removal steps and a video tutorial.