Moth3r said:Re-install the OS.
And make sure that OS is Linux or OS X.
Sorry, I know it's a dick move to tell Windows users to switch to something else when they ask for help.
I was one of the fortunate ones who never had a virus or trojan (to my knowledge) in all the years I was a Windows user. The only advice I can offer is the same as Moth3r's. Nuke and pave.