The switch has an orange coloured glow light which is on when the switch is in the operating position.
The P switch No.15 is in the second row, beneath the switch row Nos.9(for the Head Up Display) to 12, as shown on page1-03 in the handbook. Details of its operation can be found on page 6-106.
You may have nudged the switch without knowing and turned the warning sound off accidently Moz. Hopefully that is all it is. I'm assuming your handbook will have the same page numbers. I know, it is dangerous to assume