Unfortunately, The .CHK files are practically useless. First you would need to identify which files they came from. Then you would need to identify where in that file they came from, and then you would have to slip them back into the file. They used to have limited utility when dealing with the ancient CHKDSK program since if you were working with text-based documents you could often patch your file back together.. beyond that most people just started making backups on other floppies, though.
the .CHK files are typically a single cluster (4K) and there can be multiple files from a single file. The data is from either clusters that were cross-linked (used by multiple files) or lost chains )(not associated with any file at all). In the first case, you cannot restore one of the files, since the cluster only has the data for one of the files that it was part of. For example if a text file and an executable somehow share a cluster, the last file to be written will be the "good" one. You might open a text file and see a bunch of garbage in the middle. So you delete it and rewrite that paragraph and save it. Later you run a program. it fails to start or crashes. Mystery? well, if it was cross-linked, you replaced part of the executable with text data. That executable data is gone, and you would need to reinstall the program.
A lost chain is similar- it simply isn't used by any file on the disk. Major file corruption can disassociate clusters from files, but with NTFS this is far less of a problem. Typically these disassociated clusters, and even cross-linked clusters are a result of disconnecting an external drive that has write-caching enabled. By default any disk that looks like a Fixed Disk has write-caching enabled. You can verify write cache settings in Device Manager. eg:
1. Right-click the Drive and choose properties
2. On the hardware tab, identify the appropriate disk drive in the list that maps to the drive.
3. Choose "Properties". This will open the Device Manager Properties.
4. Select "Change Settings"
5. In the "Policies" Tab, turn off "Enable Write-caching on this device". It's usually safe to use this for fixed, internal disks. For hot-swappable/USB devices you'll want this disabled, and a lot of external hard drives look like standard Fixed Disk Drives to the Operating System.
You would need to identify the file it came from by looking at the 4K block and somehow "knowing" which file it came from, particularly since that data is now missing from the original file so you cannot search for it- then you would have to know where in the file it came from as well as how to patch it into place.
