my music is copying in drm format how do i change this so i can listen to m?

mps is IItronics IK06060081441 all my music has been copying fine to my mps until i tried to copy a new cd. it has gone onto my other mps fine but not my sons. it says that it is drm mode and unknown format is displayed. i have deleted all files from mp3 incase it was a virus but it still wont let me put the cd on.
Please help as i am a novice at this as it is, and im pulling my hair out.
P.S. My son has lost instructions for mp3