My Pioneer DEH-P4900iB constantly has MUTE on the display panel and I can't get any sound from it or do anything.

SOURCE: PIONEER DEH-P7700MP/P770MP CD/MP3 Faceplate

do you want the detachable face or the case to hold the detachable face?

Here is the detachable face at the Pioneer site:

http://parts.pioneerelectronics.com/part.asp?productNum=XXA7322

Here is the case for the detachable face:

http://parts.pioneerelectronics.com/part.asp?productNum=CXB3520

You might find the face, or even the whole radio with face cheaper on ebay.

SOURCE: pioneer car cd player stuck on mute

You have to isolate yellow-black cabel. This cabel was in contact with earth and it was the reason, why you have Mute on the display.

SOURCE: i need wiring color coding 4 pioneer deh 2050mpg?

Not to question you about the red being constant power but I have a pioneer deh-1600 car stereo and red is hooked to electric terminal controlled by ignition switch (on/off) and if your unit has a yellow wire that goes to constant power. The only problem with hooking up the red wire to constant would be if you happened to accidentally leave your player on it could drain the battery. Hope this helped a little. Good luck.

SOURCE: Pioneer DEH-P4900IB Changing Time and Date

1st wait till the Pioneer logo is scrolling across. Then hit the Function button for 3 - 4 seconds.