iMac function keys stopped working (f1-f9)

I have the recently updated Mojave 10.14.6 on my iMac. I have been facing a strange issue with my magic keyboard since past many days. Strangely, the function keys f1 to f9 (including the brightness keys till the play next keys) have stopped responding.

These keys were working alright before the last 2 updates. Now they suddenly stopped working exactly like a girlfriend breaking up over the phone!!

Pls help as these keys are very important. i cant control the brightness neither can i operate smoothly on other softwares with require function keys.