CHK File Recovery is a professional tool for recovering your .CHK files. It scans the contents of the .CHK files and determines the correct file types, then recover it effectively.

Windows’ built-in chkdsk tool, short for “Check Disk”, creates this folder and file. Windows automatically runs Check Disk when it notices a problem with a file system. Those .CHK files are fragments of corrupted data, Check Disk puts it in a folder for you.

Disk errors. Usually because a sudden shutdown while the relevant files were opened.
Unplugging the USB Flash or the SD card without using the safely remove device.

Try to identify the file type manually. If still does not recognize the file type, it means the file has been damaged and cannot be recovered.