Numeric side of keyboard stopped working

You mean you have a keyboard with a numeric keypad on the side, or the regular numbers at the top row?

What do you see in the keyboard viewer? Does it show you the keyboard with the right layout?

If you do not know how to access the keyboard viewer: go to system preferences->Keyboard and check the box for "show viewers for keyboard, ... in the menu bar". Then click the little flag in the menu bar for your keyboard localization, and choose "Show Keyboard Viewer".

The system does not seem to be identifying the keyboard correctly.

Try resetting NVRAM and, perhaps, resetting the SMC.

To reset NVRAM, hold down the four keys command-option-P-R immediately after pressing the power button, let it play the chime a few times, and then release the keys.

To reset SMC, look here: Reset the System Management Controller (SMC) on your Mac - Apple ...

Keyboard - Numeric Keypad Doesn’t Work