UnCHK is a lightweight, yet handy tool designed to help you recover lost files due to Windows or application crashes. It can change the extension of CHK files, which are lost fragments of files that did not close properly due to system failure.
The application does not have an actual interface, as you just have to drag and drop any CHK file on UnCHK.EXE in order to start the recovery process of all the CHK files in that same location. An alternative is to run the executable and browse for the file you want to retrieve. There is a limit on how many CHKs can be recovered from the same directory, thus you might have to move some in a sub-folder.
During the retrieval process, the original CHK files are not damaged, as backup copies are created in order to prevent data loss. Several file formats are supported, such as images (JPG, PSD, GIF, BMP), archives (ZIP, CAB), portable executables (EXE, DLL), documents (DOC, PPT, XLS, PDF, RTF), multimedia files (WAV, MID, AVI, MP3) and more.
If you drag and drop another file type onto the application, an entry is automatically generated in the INI file in order to remember the extension in the future. However, this only happens if the file has a standard header.
UnCHK also comes in handy when your entire hard drive is corrupted and the ScanDisk function is not able to fix it, as it can try to recover file pieces from the original FAT system.
One drawback of the program is that it cannot identify the end of files or detect whether they extend into another CHK file or not. This means that if the file to recover is fragmented, only the first fragment can be recovered.
Despite that it can generate false recoveries, UnCHK is a tool that can assist you in retrieving improperly closed files. If you lost important data due to system crash, it is worth trying to recover information from the existing CHK files.