If you ask Packard Bell, I believe they will sell you a disk that will enable you to reformat the computer back to the condition it was in when it left the factory. I can't remember the cost, but I suspect it's approaching £40.
Before you do that, did your friend ever create a restore disk when he forst got the computer? If not, then you may still be able to do it. PB computers usually come preloaded with software that will create a restore disk once.