I tried this, but it isn't working for me.

I downloaded SystemRescueCd  ---> http://www.sysresccd.org/SystemRescueCd
I booted from a DVD and went straight to the GUI, had terminal open, typed in exactly what is written in the OP and I get an error in terminal.

After I type the part with "sudo ....."
Terminal responds with:

zsh: correct 'sudo' to '_sudo' [nyae]?

If I press y: _arguments:comparguments:312:can only be called from completion function
If I press n: zsh: command not found : sudo

I have 4 hard-drives and 1 SSD. I disconnected all of them and connected the 1 hard-drive that I need to run the recovery tool on (this HDD is not bootable). It's not connected to the number 1 SATA port on the mobo. Does this therefore affect the part of the code with:  '/dev/sda'? Or what's going on?