phone will not ring?

Question - mend, repair, fix

I have had my Binatone symphony 2210 for three years. My autistic sons (I have three) have somehow changed one of the `phones so that it will not ring.Not a problem in most cases but I am a paraplegic and I need a `phone in at least three rooms.one of my `phones has a logo that indicates it will not ring, can anyone tell me how to reset it so that it will ring. Any advice will be most welcome.
thankyou
Big Steve

nawaz m
March 2020

To switch the handset’s ringer off/on

Press and hold the
* button for 2 seconds to switch on
Press and hold the same button 2 seconds to switch the ringer off

BTECH
February 2013