my iMac is around 9 years old and I already face another problem where in I have to reset the SMC, this I done by removing the power plug from the mains for sometime and then switching on same. I believe there is no other solution to this issue. Regarding Bluetooth icon, it was definitely missing, I checked the right top end menu bar n could see the Bluetooth icon but it was not highlighted n showed as disconnected. As a last measure I reset my iMac by shutting down the machine n removing the power plug for a few minutes and then plugged it back n switched on the iMac. Luckily it worked n the Bluetooth icon is now highlighted and the Apple cordless keyboard is now working. So for now this issue has been resolved. Do we have any permanent solution for this SMC issue
thanks for all your assistance and guidance