Hi,
I'm not familiar with factory restore with all systems since different manufacturers tend to have different restoring procedures. But if you've done factory restore successfully with this system earlier and same procedure doesn't work now then factory restore from recovery partition obviously won't be an option now.if there is anyway you can just help me be able to do a factory restore I would be just as happy.
Did your computer come with Windows 7 installation media? If not then there should had been an option to create recovery discs (I hope you have done that before the system got infected).