How can I fix a sony walkman cd/mp3 player?

I have a Sony Walkman D-NE320 Atrac3plus MP3. Recently it stopped reading cds put into it. It has power and registers when it opens/closes/Cd is put in there, but when trying to read the CD (both audio or mp3 cd) the loading signal keeps swirling until it turns off by itself without registering the information on the cd.

I'm wondering if some part of the hardware is damaged or misplaced (since sometimes I can be rough with my stuff). How can I repair it?

jc
January 2011