iMac keyboard issue

I am assuming it is a wireless keyboard, if so please follow the steps below:

The following will require any USB keyboard and mouse. If you don’t have them, borrow or buy them, they are inexpensive!

1.     Connect the USB keyboard and mouse to the computer.

2.     Open System Preferences – Bluetooth

3.     Un-pair the wireless keyboard and mouse.

4.     Turn off Bluetooth

5.     Restart the computer in Safe Mode per the directions in Use safe mode on your Mac - Apple Support

6.     Restart the computer normally.

7.     Open System Preferences – Bluetooth

8.     Turn on Bluetooth

9.     Re-Pair the wireless keyboard and mouse.

10.  Unplug the USB keyboard and mouse and begin testing the wireless devices again. 

Plug in the wired USB keyboard and restart the computer in Safe Mode. It should startup, if you forgot your password and cannot log in then you have an additional problem that be solved with the steps in If you forgot your Mac login password.

BTW, do you have any of the following third party apps installed on your Mac?

·      Antivirus Apps

·      Cleaning Apps

·      Security Apps

·      VPN Apps

·      Maintenance Apps