MacBook Air (13-inch, Mid 2012) built in keyboard problem My keyboard has suddenly stopped working properly.

I can only write by using the keyboard viewer!

Basically the characters: ijklmno u and a few other keys don’t work on the Mac's built in keyboard.

System information:
MacBook Air (13-inch, Mid 2012)
1.8 GHz Intel Core i5
4 GB 1600 MHz DDR3
Graphics Intel HD Graphics 4000 1536 MB
Mac High Sierra 10.13.1

Also not able to modify system settings for scrolling.

Any solutions are appreciated!
This sounds like a hardware failure since all the keys that are not working are around one area. You may have to consider using a USB or Bluetooth keyboard with your MacBook Air. Repairing the keyboard may be expensive.