Problems antivirus cannot remove the virus

These few months I am very confused, because there is a problem in my computer. I am trying saya. sudah way to solve that problem. I mean the problem of computer viruses. Many of my friends suggested that Antivirus downloaded on the internet for free there.
I tried suggestions from friends and finally I installed a free Antivirus. For a month I use the Antivirus software and it was running fine. In August I checked my computer and my computer was getting worse than it becomes. My computer is made to die by a virus because I used Antivirus that does not work to eradicate the virus. All of my data turned into shortcut.
Please give me a solution to eradicate the virus? including what is it? why I can not remove the virus?
