One of my lovely family members (who can hardly use a PC) has managed to get a virus on their PC

basically the PC wont allow you top open any files or even the internet (it flashes up the disappears)

now i'm hoping i can start the PC in safe mode, and try and sort it that way (is it still hold f8 on boot up?)

If i cant do this i'm tempted to restore the PC back to factory settings using the restore disc, but he's lost the restore disc!

so my question is: how do i restore the pc without the restore disc if i need to do it?

Matt