I accidentally started a backup from `/dev/sda3` my root partition that is formatted as `ext4` to my backup hard drive `dev/sdb2` which was formatted as `NTFS`. I did this using the `dd` command:

```
dd if=dev/sda3 of=/dev/sdb2

```

When I recognized the mistake I canceled the command, but now when I run `lsblk -f` it lists the backup hard drive as `ext4`. 

I am also not unable to mount the disk. I receive this error:

```
mount: /media/HD: wrong fs type, bad option, bad superblock on /dev/sdb2, 
missing codepage or helper program, or other error.

```

Is there anyway to rescue any of the files on the hard drive that may not have been overwritten?