About 2 wks ago i uninstalled a freeware which forced a restart and since then i haven't been able to access the data hard drive . All i've been getting is error msg: 'the file or directory is corrupted or unreadable'. It has about 1.6TB data in it.
The HDD is bitlock encrypted but i have now set it to automatically unlock on my pc, and i have also removed it from inside the pc and it is now attached via a USB cable.
Here is the screenshot and the log file. Thanks.

Testdisk logfile:
Wed Apr 18 01:06:16 2012
Command line: TestDisk
TestDisk 6.14-WIP, Data Recovery Utility, March 2012
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org
OS: Windows 7 (7601) SP1
Compiler: GCC 4.6, Cygwin 1007.9
Compilation date: 2012-03-25T21:26:26
ext2fs lib: 1.41.8, ntfs lib: 10:0:0, reiserfs lib: 0.3.1-rc8, ewf lib: 20100226
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(/dev/sda)=160041885696
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(/dev/sdb)=2000398934016
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive0)=160041885696
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive1)=2000398934016
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\C:)=159934054400
filewin32_getfilesize(\\.\D:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\D:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\D:
filewin32_getfilesize(\\.\E:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\E:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\E:
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\F:)=2000396289024
Hard disk list
Disk /dev/sda - 160 GB / 149 GiB - CHS 19457 255 63, sector size=512 - Hitachi HDS721616PLA380, S/N:202020202020565039463437485a35304c484e35, FW:P22OABEA
Disk /dev/sdb - 2000 GB / 1863 GiB - CHS 243201 255 63, sector size=512 - SAMSUNG HD204UI, S/N:152D20337A0C
Partition table type (auto): Intel
Disk /dev/sdb - 2000 GB / 1863 GiB - SAMSUNG HD204UI
Partition table type: Intel
Analyse Disk /dev/sdb - 2000 GB / 1863 GiB - CHS 243201 255 63
Geometry from i386 MBR: head=255 sector=63
check_part_i386 failed for partition type 07
get_geometry_from_list_part_aux head=255 nbr=2
get_geometry_from_list_part_aux head=8 nbr=1
get_geometry_from_list_part_aux head=16 nbr=1
get_geometry_from_list_part_aux head=32 nbr=1
get_geometry_from_list_part_aux head=64 nbr=1
get_geometry_from_list_part_aux head=128 nbr=1
get_geometry_from_list_part_aux head=240 nbr=1
get_geometry_from_list_part_aux head=255 nbr=2
Current partition structure:
Invalid NTFS or EXFAT boot
1 * HPFS - NTFS 0 1 1 243200 254 63 3907024002
1 * HPFS - NTFS 0 1 1 243200 254 63 3907024002
Ask the user for vista mode
search_vista_part: 1
search_part()
Disk /dev/sdb - 2000 GB / 1863 GiB - CHS 243201 255 63
Search for partition aborted
Results
Change partition type:
HPFS - NTFS 0 0 1 243200 254 63 3907024065
interface_write()
No partition found or selected for recovery