Synchronize to continue your music subscription

Question

When we download the songs to the player it shows up in the player but the message synchronize to continue your music subscription pops up and will not play the song. How can we fix this?I keep trying to play the music that i put on my mp3 player but the message "synchronize to continue your music subcription" how can i delete these songs off the mp3 player.My Sansa model:e250 MP3 has been providing me with great service for two years. I have not added or deleted any music. Suddenly it is now telling me "Synchronise to continue your music subscription" and it won't play my music. What does this mean and why has it suddenly started to do this and what can I do to get my music back?