How do i solve "player error Unable to play (song) on my Verizon LG music phone?

Ok so i got a micro SD card and put music (wma format) from my computer and put the card into my phone....it transfered the songs to my library but when i go to listen to them...i choose a song (and this happens with all the songs) and its says Player error unable to play.....What can i do about that to fix it??