|Restore with the Packard Bell Recovery discs. This will wipe the C drive contents and put everything back to when it was new. You are supposed to make the PB Recovery Discs yourself from within Windows when you first get the PC so I hope you made them.|
Better still, you could have made a "disk image" of the C drive on to an external drive, using free disk-imaging software.
That makes an exact copy of everything on the C drive, including your own files, Windows, settings, your Desktop layout etc. But if you haven't already done that it's too late to help you now.