How can I recover data from a 2TB hard drive?

ddrescue

To recover data from a failing hard disk any further read or write access to this drive needs to be avoided as this dramatically increases damage and may eventually lead to a complete failure to access this drive.

It is therefore recommended that you first read all data that are still accessible on your drive by creating an image of this drive. Recovering your data can then be done from this image.

Ddrescue is a tool that allows copying all data from your drive and save it to either another (healthy) drive, or to an image on a healthy drive. The drive you save your image to needs to be at least of the same size as the original drive was.

There is a detailed guide on how to do this on the Forensic Wiki. The first step will be to boot your system e.g. from a live rescue system or CD and run the following command in a terminal:

ddrescue --no-split </dev/hda1> <imagefile> <logfile>

Replace above <entries> according to your system setup.

You can then perform data recovery e.g by using testdisc or photorec on the generated imagefile.