After a torrent of angry Seagate Barracuda owners voiced concern over their failing disk drives, Seagate has fessed up to the issue. According to Seagate, a firmware bug in DiamondMax 22, Barracuda 7200.11, and Barracuda ES.2 SATA drives could make the disks “inaccessible when the host system is turned on.” Seagate assures owners that their data is not lost (it's still somewhere on the disk). However, should data loss occur, Seagate is providing free data recovery services on a case by case basis.
Check your Seagate drive here.
If your drive is one that affected, a link is provided at the bottom to contact Seagate to expedite resolution. They also have a piece of software at this link to check your drive. It is good of Seagate to recognize that they have a problem and to do something about it.