If that packet of court papers is not in the "right" file box, try the box before and the box after and remember that files in any box of court papers may not be in order.
It is also possible that a researcher was using two separate file boxes and switched the boxes in which the files were supposed have been placed. Packets of papers usually have the box number written on the outside. Look in the box where the missing file is supposed to be and see if a file is in the wrong box. The box where that file is supposed to be may be where your missing file was accidentally placed.