I built my computer about 3 months ago. It has a Seagate Barracuda 7200.12 1TB HDD (model ST31000524AS) on an AsRock 970 Extreme Mobo. My HDD was split into 3 partitions, a partition for windows 7 ultimate 64bit, a partition for ubunu 11.04, and a partition I use to store files. Last night I went to bed while my brother was playing Skyrim on my computer. He said there were no problems when he went to bed last night, but when I woke up this morning, I received the POST message "Reboot and Select proper Boot Device or Insert Bootable media in selected boot device and press a key". I tried switching both the power and sata connections on my CD drive, which still works., and that made no difference. I have no devices except for my monitor plugged in. What's more is that in the UEFI, it doesn't even show my HDD, and when i try to run windows 7 repair with the installation disk I have, there are no Operating Systems, partitions, or any other things to be repaired.
EIDT: After running seatools for dos off a cd, it instantly failed the tests because it could not access the drive. I had a friend put it in his rig and got the same results.