HELP: External hd stopped working. Not recognized in “disk manager”.

I have a Conceptronic Hard Disk box (200GB) that worked fine until a couple of days ago. It suddenly stopped working (while beeing in use) and now it doesn’t appear in “my computer” nor is it recognised by “disk manager” although it does appear in “device manager”.
I’ve tried the HD in other computers and the same thing happens…

I am basically worried for the 200GB worth of personal information that’s inside…

Any ideas?
Thanks
Monica

PD. it sometimes makes a funny noise as if something inside was broken (maybe the fan) but since it does get installed when connected to a compute I figure there’s still hope?