Hard drive problem

[Talikira]

Okay, so... One part of my HD section started... not working. Like, it just reverted to a "Local Disk" drive, and it asks me to format it when I click on it. It was working fine earlier this evening, but now all the files seem to be gone.
When I was going to "My pictures" I clicked on my Pictures HD section(The one that reverted back) and it said that "The disk in drive D is not formatted. Would you like to format it now? Yes/No"
So I'm not exactly sure what's going on. Does anyone have an answer? Is this fixable? I don't want to lose all my files in that section. I don't know why, but it's just that particular part of the HD. I've tried restarting, but that didn't work, and this HD is fairly new.

I'm not sure if it has to do anything with my computer crashing/freezing lately... I'm not sure whats causing that, either. Once, all of my new HD files just, disappeared, and my computer reverted to the old one. (I have two) but I restarted, and it was back to normal.

So any ideas on how to fix this? If there is a way, please tell me. Thanks.
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By the way, I have Windows 2000 professional if that means anything.