Today my external hard drive suddenly become RAW meaning i couldn't mount it in windows or even in linux and worse I couldn't even run chkdsk utility in windows then i came across this utily called ntfsfix while searching for the solution.
The following is from the ntfsfix manpage:
ntfsfix is a utility that fixes some common NTFS problems.ntfsfix is NOT a Linux version of chkdsk. It only repairs some fundamental NTFS inconsistencies, resets the NTFS journal file and schedules an NTFS consistency check for the first boot into Windows. You may run ntfsfix on an NTFS volume if you think it was damaged by Windows or some other way and it cannot be mounted.
so to run ntfsfix become root and give the following command
# ntfsfix -d /dev/sdb1
it will fix the most common errors in the NTFS partition.