Hy!
i have a external hdd Seagate 2Tb Serial Number: Z1E1W7R5 Part Number:1CH164-572 Model Number:ST2000DM001 Family:BARRACUDA firmware CC44 .After 3 years i face with a big problem the hdd is detected with 3,9Gb make 2 clinck and disk stoped.

Thank's.

Heads are bad. If you see disk is not recognized by full model and s/n. That one that you see is information from PCB.

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Sistrum Data Recovery
http://www.sistrum.mk/en

clicking + stopped is not a good sign, most likely head problem.
was it dropped ?

if you have important data on drive, it is highly recommended to send it to a professional DR company.

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Data Recovery Pakistan

The HDD was connect to a Asus router RT-N16 and never drop ,router and hdd have uninterruptible power supply .

warranty ends = life ends

I would say you are lucky to survive 3 years with a DM series drive.
the more you power up the drive the worse you will make it.
if data is worth, send it to reputed DR company.

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Data Recovery Pakistan