There are two ways,
1, If you still can access Windows, try to disable any backup programs,
virus scanning programs or disk defragment tools. Try also to run a
hardware diagnostics tool to detect any errors your hard drive might
have. And run chkdsk /r to detect and repair any file system structural
2, If you are unable to load Windows. Then you should try to access
your ntfs partitions by making a ntfs boot disk with NTFS4DOS
(freeware). You can download it from http://www.geekswhoknow.com/files/ntfsinst.exe
You will need a floppy disk.
After you load the bootable floppy disk onto your damaged system,
select either option one (1) or option three (3). If you selected
option one (1), type chkdsk /r at the command prompt, and your problem
should go away after the disk has been repaired.
Note! Unfortunately there is a chance that your partition is corrupt
beyond repair and all of your data is lost. In that case, you need to
reformat the partition to be able to use it again.
Additional information can be found at http://support.microsoft.com/default.aspx?scid=kb;en-us;Q228888