une petite explication en anglais:
Those are recovered lost cluster chains. The clusters might get lost when file operations are interrupted abnormally. In the case of an USB flash drive, that might happen when you physically unplug the device before "Safely Removing Hardware" (actually, before the OS has finished writing cached data to the medium).
A single .CHK file may contain
a single entire file (or multiple entire files),
a part (or multiple parts) of a file (or multiple files) or
a really messy mix of the above.
Most often recovering something useful from those .CHK files is an extremely complicated (though, not entirely impossible) thing to do, thus, most often, it is just less of a headache simply to delete them and forget what happened.*
donc voila c'est très compliqué de récupérer ces fichiers apparemment, il faut essayer plusieurs softs de récupération et si ca marche pas il faut formater tout simplement!
