If you have any media in the drives, remove it and reboot. If you have a thumbdrive, disconnect it, on some systems it will stop the boot process. If that doesn't work change the boot up sequence, putting the HDD as first boot.
If its asking you for a password when going into BIOS, try resetting CMOS by pulling the watch battery out of the motherboard for 5 seconds then putting it back in. That might clear that password.
Sounds like your MBR is hosed...Google "Repair MBR" for a detailed step by step. It could be a mechanical problem with your HDD or it could be from a virus....at any rate if you aren't seeing your HDD listed in your BIOS, you have a large problem.
actually messing around the with my computer tower today, I disconnected where my hard drive was connected to my MOBO and used another connection next to it and it fixed the problem, thanks for the help and advice