I know this may sound trivial but I use this all the time. Saturday morning was listening to a pod cast on my phone, 30 minutes later the button stopped working. Does anyone have a solution? The car is 18 months old so still under warranty.
Probably a warranty issue. I have seen the satellite radio need a power down of the car to work properly but I am sure you have tried that.
By power down, if you mean turning the car on and off yes, if you mean completely disconnecting the battery no. Heck, I don't even know where the battery is.
Your description is scant, but it sounds like you lost bluetooth communication. This is not unheard of with some phones, and can be caused by a variety to things. That button is expected to be greyed out when no source is detected.
Not bluetooth, don't think mine has that function. There is a way to connect your phone through the center console box between the seats to an auxiliary cable. The switch on the radio face says Disc/Aux. I thought I was actually pretty clear.