m240 shows`"no files"

i just got an m240 and can make it play songs and the radio, but when i transfer audiobooks, either downloaded from audible or copied from a purchased cd, they show up as being there on the computer screen but there’s “no files” on the player.  i looked up changing the mode in the user guide but “modes” does not seem to be there on my player.  i reformatted according to intructions in this forum: still no files.  any clue? ll i got it for was to listen to audiobooks.

HAD SAME PROBLEM. PC COULD NOT SEE  IT. NO DRIVER FOR m240 Mp3 Player. No help FROM SANDISK

Installed Windows 11 media player NO PROBLEMS PC SEES IT STRAIGHT AWAY. 

Had the same problem: I changed the battery, and for some reason it came back.