recorded something..Now, when try to listen, "Error, can't open this file"

HI everyone, thank you for taking the time to read this thread! I have a Sandisk Sansa m230 mp3 player.  I recorded something really important and wanted to listen to it a lil while after I recorded it…When try to listen to that recording, I get message, “Error, can’t open this file”. 

(B4 this recording was taped, I was having a lil bit of difficulty with the mp3 player…it was FREEZING when I was trying to record something b4 this…)

My question is: IS there ANY way I can listen to this recording…it’s a very valuable recording!

ANY ideas of what I should do???