The standard solution is to restore your last image or reinstall your OS, but there might be a repair option if you have the OS install disk.
I think I have a trojanm virus as I can not acess start or any programmes and my task manager is disabled. When I log in either normally or through any of the safe mode options it goes to a screen saying I have to pay £100 for downloading illegal music, which I have not. Any ideas / suggestions would be welcomed. Thanks.. (I do have an anti virus malewarebytes but I can not run it as I can not get to it. Thanks, Rob