I know this question is from 9 years ago, but I saw it and thought I'd answer just for kicks.
It sounds like your hard drive is dead. If both your BIOS and Ubuntu couldn't detect it, then that rules out software, so it has to be hardware. You'll need a new hard drive. There is no info here on iFixit about what hard drive you'll need, but I'm sure you can dig around online and find something. Here is a guide on removing the motherboard ([guide|2919]) ; in steps 36 and 37 it addresses the hard drive area. After you remove the cover, you should be able to unplug and lift out the hard drive. While you're at it (if you still have the computer after all these years), you might as well create a guide ([[Info:Repair Guide]]) so you can help someone else who may be having the same problem.
Let me know how it goes!