Your description does sound like an unrecoverable hard drive failure.
If you need to have data recovered, it will be expensive.
The only thing you can do is check with Seagate to see if the drive is still under warranty, and replace the drive. If you think you plan to get data off the drive professionally, Seagate has an option to send you the replacement first so you can copy your data over, then return the broken one.
http://support.seagate.com/customer/en-US/warranty_validation.jsp