You have no power at all? The leds don't light up? The disk doesn't spin up? No noise?
I'm affraid recovering the data is not going to be easy or costless... a physical error means in most of the cases: ship your drive to a lab (clean room) to recover the data.
If you can power up your drive you will be able to recover the data yourself, but else I advise to take it to a recovery lab:

- For instance Ontrack will help you out. They are authorised to open up Seagate disks without voiding the warranty (but your warranty has probably expired)
http://www.ontrack.com/easyrecovery/

- Data Recovery Services Inc.
They will try to repair your drive to ready state, so they can pull a raw image from the platters and put that on a medium of your choice, CD-R, another disk, ...
http://www.datarecovery.net/HDD_Recovery.asp

- DataRecoverygroup
Data recovery group is specialised in Hard Disk recovery after harddisk crashes or failures.
http://www.datarecoverygroup.com/

I bet you can find more of those companies by searching in google.