Okay, so here's basically what happened. Most of this was fault on my part..

So I was trying to clear a virus that kept reappearing in my computer, so I deleted some system files, believing them to be malicious. What I didn't know was, I think some of them were files to detect my Hard Drive!

I've tried unplugging the power socket and reconnecting the wires to different ports (SATA1, 2, etc), but the same thing always appears, 'Cannot Detect Harddrive, please insert setup disc (which I assumed was the XP disc)' which I did. But it won't even let me reformat because the Hard Drive cannot be detected!

What i'm looking for is possibly...perhaps a boot disc (not floppy, my cpu doesn't have that..) that recovers all of your C:\Windows and System/System32 folders. I'm not even sure if something like that exists, but without it my computer cannot even detect a hard drive.

Please help, and thank you for your kind attention!

First do the most obvious witch is go to you're BIOS and see if you can detect the HD in there. If you cant see it there than open you're pc case (If you're comfortable with the workings inside) and remove the data cables and reinstalling them properly. SATA(Serial ATA) Should be configured properly in the BIOS in order to work and should be enabled in the BIOS.

Oh, it can't even detect in BIOS. It's as good as not having a hard drive there at all...because the same error occurs when I unplug the hard drive and start the computer...