Many thanks for your responses. Yes, Rock are a reputable UK laptop manufacturer; I contacted them on Saturday and they are sending me a new hard disk. They also said that it might be the motherboard, in which case the laptop will have to be sent back for repair.
I was interested in what you said, GX1_Man, about using Linux to possibly recover some of the data on the hard drive. I'd assumed that I'd lost it all (fortunately most of my data is backed up to an external drive, but there are programs that I'd like to be able to access if possible). I don't know the first thing about Linux, or Slax, so would be grateful for any step by step guidance on what I need to do.