|Explain what you mean that avast doesn't work?|
Live one-care is not real good.
Try malwarebytes and remove all it finds.
Try scheduling a bootscan with avast and run that, moving all it finds to the chest.
If you had norton on before avast, I'd suggest using the norton uninstaller from their website to remove it.
Some HELP in posting on Computing.net plus free progs and instructions Cheers