oh dear - that doesn't sound good.
I was going to suggest checking the disc ... but if you can't even get to a comand prompt ...
it sounds as if your HDD is either corrupted ... or physically damaged.
you could try (or getting a chum to) create a knoppix startup disk
http://www.knopper.net/knoppix-mirrors/index-e n.html
you can then use the CD to startup ... and if the files are still there copy them to a memory stick or external HDD.
it all depends on how you feel about getting your hands mucky
if it seems a bit daunting ... maybe a chum - or the final choice a local PC shop