Yes.
Depends on what the virus actually did to hid them. For instance, if you name a file with a leading . then the file is hidden. For example: .apple.txt would be a hidden file. If you enable hidden files to be shown that might do it.
opening an email attachment downloading stuff from the internet
A virus that hides in a file that, when you run it, infects your computer.
A hidden virus may copy and distribute itself throughout your computer, since most viruses are hidden deep in your computer, it cant do much more than duplicate.
A computer virus that infects application filessuch as spreadsheets, computer games, or accounting.
steam is no virus
.exe file
There is away. there are some free online scanners out there to scan your computer but cant delete them. they should tell you where the virus is hidden. go to search and look in everything and make sure you set the advance seting to seearch hidden files and folders. once you find the infected file delete it from your computer. make sure you empty your recycle bin. BUT! if a virus is hidden in a pathway you need antivirus or to reformat your computer. deleting viruses manualt may harm your computer
Delete the system32 folder on your computer
norton anti virus of course
download "noob killer"
The infect your computer by being undetected by your anti virus and posing as a harmless file.