Audio Systems: pioneer dehp520 mute stuck, mute button, question title

Question
the screen show MUTE but theres no mute button, and nothing connected to the mute lead no response to volume o audio controls everything else working but muted, please help
-------------------------------------------
The text above is a follow-up to ...

-----Question-----
title says it all but out of nowhere its stuck in mute and i can not do nothing about it i have replaces the pal005a but still the same, please help!!!
-----Answer-----
does it actually say the word mute on the screen or does it just not make any sound?  If it doesnt say mute or there is no indication its actually in mute, do you remember ever seeing any indication when it was in mute (when it was working right?)  is there even a mute button?
thanks!

Answer
there may be a mute button you dont know about,  it's possible that just disconnecting power from the unit and letting it sit unpowered for a few days may just clear the memory and it will go back to non muted state.  you can either remove the unit from the car or disconnect the car battery.  try it after 1 hour first and if that doesnt help try it after 2 days.  sometimes the memory in those things can stick for a long time (48 hours or more).  if that doesnt help it may just be broken.
Good luck!