:/tmp$ sudo testdisk /debug /log /dev/sdbTestDisk 6.14, Data Recovery Utility, July 2013
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org

Unable to open file or device /dev/sdb

PhotoRec does not find the partitions either.

It hast no external power supply. It is a 1TB external HD with no external power supply. Maybe it is because of that... But it was sold as "no external power needed"

try another usb port (especially the one with a lightening bolt next to it).
(or one labeled esata/ss)

i think the drive mite be too powerful for standard usb.

Hi,

I feel your pain and frustrations. Does the USB for the drive have two connectors on one end? If so you need to plug in both to ports to provide enough power to the external drive. As suggested, you can use a powered hub in hope of providing power & access to the drive. You could check with a different USB cable to ensure no issues there.
[mod hat on]
In post #12 you used foul language and this violates LQ Rules. I can understand your frustrations but try to not include that language. [mod hat off]

You should try a LiveCD/DVD to see if the drive is recognized. By using the live system you are excluding a possible installed system issue. With Clonezilla you can boot and have utilities available to copy, move the filesystem in question to another storage media.

You can find other tools at:Hope this helps.
Have fun & enjoy!

Sorry but did you ensure using 'dmesg' output the device was actually available as "/dev/sdb"?
Did you retry this?

If everything fails please try (a couple of times) to extract the starting 2 mb of the disk: then tell me where I can pick up the file (Send me an email? No file sharing services please).

I thank you ALL for your help. Really. With all my best wishes.

I tried too the last things you have recommended me but it didn't work. I can't even format the HD anywhere. It really seems that the HD is dead. I have tried everything. Seagate tools to check the drive healthness say that "it is quite possible that the HD is damaged". I give up

Once again, I thank you all for your empathy

Did you put this drive in the enclosure or was it in the enclosure when you bought it?
If you put in the enclosure it could be the enclosure.

What do you mean by enclosure?

Did you buy the drive as 1 unit, or, did you buy the enclosure & put it inside of it?

Yes, as 1 unit

I asked because I have 2 enclosures & 1 went bad, so maybe it's the enlosure. $15 for a new enclosure is worth the risk. I would consider it. Other than that your only other option would be to RMA the unit which should have a 2yr warrantee.