Thanks for all the advice.

I should, as John pointed out, have mentioned that my operating system is Windows XP and I'm using a PC.

Virtually everything on the malfunctioning external hard drive was already a copy of a CD I own. There were just a few files of traditional song and music which had been sent to me as MP3s. I've managed to recover those.

The drive was only six months old. Not a very long life.