How can I Fix No volume Issue on PSP

Hi techyv Experts ,
I have come here for a little issue to my Sony PSP device. I want to fix No volume on PSP device but I can not. It has been occurring since five days. When I play a song it remains cool for a while but after 5-10 minutes it shows that no volume on PSP.
I have checked the Automatic Volume limiter system but it was remained cool. I can not understand where the issue comes from. I have sought a hardware expert but he did not solve my issue. Any one can tell me how can I solve this issue?
