"Could not boot from disk"?

Okay, so I left for the weekend, turned my computer off thursday night, came back monday, and now my computer won't turn on. Instead, after the initial bios dealy that flashes up and talks about what's all connected and such, the screen goes black, then simply displays "Could not boot from harddisk, please enter system disk" or something close to that. I checked my bios, and it still reads my hard-drive as being there, and I opened my case and looked around inside for something that might've come loose. Everything seemed to be in working order. It also won't let me do a system restore.

What would cause this to happen? Nobody went on my PC during the weekend as far as I know, and it's also password protected. It was also disconnected from the internet. What're my options here? I don't have a system disk around my house (university home, disk is a 6 hour drive away) and I'm kind of on a tight schedule right now (fucking finals), so I need the quickest way to fix things. Is there -anything- I can do, or, since I'm not terribly computer savy, am I left having to take it to a shop or something?

If you're desperate just to use the machine, perhaps a linux live cd will fulfill your needs.

Not great, but better than nothing.

Will that give me access to all my data? I've got some stuff that's crutial to some projects I need to do...

I'd like to get everything back and running like it was ASAP :/

That depends on what happened to your harddisk. It seems as if your HD is being detected properly, but it doesn't have a proper boot sector.

If it's just part of the MBR that's toast, you might still be able to access the data with a live disk. If not, more complicated (and dangerous) procedures may be needed.

Sigh. Not agreat thing to return home to :/ I get the feeling I'll end up having to take it to a shop, but I really, really hope I can find someplace or someone to lend me a boot disk.. Would they be purchasable for XP?

And what kind of more dangerous procedures would be needed? :/