Call PB on 0870 513 3332 with the PC serial number, explain the problem, and they'll send you a set of back up CDs - for around £30-40. Probably worth paying just to have them in future though....
When you have recovered the machine, go to the PB
website and download the Bootdisk Creator for the appropriate model, it will back up everything required for a full recvery to a CD-R, assuming it has a burner of course.