The NTFS system maintains an entry for each file/folder and indicates which cluster(s) hold its contents. This error signifies that there was a failure to read that entry, not the actual contents, which usually remain intact within their respective storage location(s).
Each file and folder is described by NTFS in a single record within NTFS’s Master File Table (MFT). If you lose your ability to read one of those records, Windows declares corruption, and yet the contents remain perfectly intact just a few clusters away.
chkdsk will rewrite the file table to ensure internal consistency; in doing so, it will discard entries it cannot reconcile. It is these same entries that a recovery attempt would have used.This is what Windows reports when it fails to interpret the entries that describe a file/folder. NTFS contains an index of all items located upon the volume. When Windows reports this, it can no longer read the part of the index necessary for interpreting a particular item (file/folder).
The information in the files themselves is frequently still there. It is the location within the filesystem of these files, and their size, that has been lost, and this is therefore a much more recoverable type of loss compared to losing the data.
The standard advice is to run chkdsk. If the data is important, then this typically is bad advice.
It writes to a disk that is already struggling. On a drive with sectors failing, the write will frequently fail to complete, and an interrupted repair operation will leave things worse than they are now.
It discards what it cannot reconcile. Chkdsk optimises for a consistent file system. Where an entry can't be fixed it is removed, and your file goes with it.
It gives no preview. You don't see what will be lost before you lose it. And there is no undo.
Check the drive health first. This error rarely appears on a healthy disk. Read the SMART data first before making any decisions.
Only if the volume matters more than the files on it (for example, a system disk that you plan to rebuild anyway). Otherwise, no.
Usually not. The index describing it has been damaged and often the content of the file is intact and accessible via other means.
This indicates that there are problems at the sector level as opposed to a file issue. Stop using the disk and check its health.
A free diagnostic is provided with each item, after which the price is fixed (from £250 +VAT for cards / USB media and from £300 +VAT for drives).