Is the SATA directly connected to the Motherboard or is there a cable in the middle. If there is a cable, it could have gone bad, unlikely, but posable. The other idea is i had the sme thing happen on my desktop, I unplugged the drive moved it to the next SATA connector, put another dirve in it's place and was getting ready to reinstall the OS and try to salvagte some of my data, when it booted like nothing had happened. Try taking the drive out dust out the SATA port with canned air and try puting it back in. I know it sounds strange, but like with mine, it might work.
Past that then I would say start looking at the boot sector and see it something has gone wrong there. Then I would say that it might be the SATA adapter or drive itself.