Adding to TTG’s post, this trick worked for me (bringing a drive back to life), but my PC wanted the drive formatting.
I formatted the drive and used recovery software to search the drive for lost files. Contrary to what you might think, formatting a drive will not erase all the data on the drive – even though your operating system will see the drive as empty. Download.com is a good source of recovery freeware.
Alternatively there are companies that will attempt data recovery from a dead hard drive, but expect to pay upwards of £1,000.
It must make a change for teachers, rather than ‘the dog ate my homework’, ‘my hard drive failed’ must be a common excuse for failure to submit homework/course work on time. Your daughter has learnt a valuable lesson about backing up work. My PC has two separate hard drives, I regularly copy important files to the slave drive, and burn to CD every few months.