Fix for 789uiojkl keys or numeric keypad not working

If typing 789uiojklm or the numeric keypad on your keyboard are not producing any output on your screen, it usually indicates that you somehow have the Mouse Keys feature activated.  Often there is no way to explain how this might have happened.  

Into order to turn it off on a Mac, you need to go to System Settings > Accessibility > Pointer Control > Alternative Control Methods and uncheck the box for Enable Mouse Keys.  Then click on ⓘ or Options and make sure the box for "Press Option key five times to toggle Mouse Keys" is unchecked.

Also make sure Mouse Keys is turned OFF in System Settings > Lock Screen > Accessibility Options

Finally, press Option Command F5 and make sure the box for Mouse Keys is not checked.

If you think you are locked out of your machine because Mouse Keys is on and you cannot enter your password, and if pressing Option 5 times does not help, try connecting a full keyboard with numpad. Mouse Keys should only affect the numpad and all the keys on the rest of the keyboard should function normally.

If you have this problem on an iPad or iPhone, the place to turn off Mouse Keys is Settings > Accessibility > Touch > Assistive Touch > Pointer Devices. Make sure the Option Key Toggle is also off.