Putting songs on computer from M240

I have a SansaM240 and I would like to know how can I put these songs, that have already been synced, on the computer? For some reason, all of the songs on my player are not on the computer.

Plug it in to your computer and then open Windows Explorer (right-click the My Computer icon on the desktop and select Explore).  You should be able to see the m240 just like it was a USB flash drive and copy the files from it that way.