Airplay icon missing from iTunes on PC

Hello:  I know this is old school, but I have an extensive music library on iTunes which resides on my PC.  Up until a few days ago I was able t stream to my Marantz CR610.  And then the AirPlay icon vanished.  Have tried every fix possible from other communities / Apple (non-support).  Anyone have an idea of what to do?  My music is being held hostage...

Thanks,

mrgeo