Keyboard not working A-L

Has anyone determined the source of the problem when part of the keyboard (MacBook Pro laptop) doesn’t work?

The problem with my laptop keyboard is only with the letters in the A-L row. Those keys won’t work in upper or lower case, though the caps lock key works with other letters.

The punctuation, number, function, and other keys all work. Like the caps lock key, the return, shift, return, and all the other operating, positioning, spacing, keys all work. The mousepad

I’ve read the comments on a previous question regarding this problem. I’ve connected an external keyboard (only had a Dell keyboard), and thankfully, it does work. But it doesn’t correct the problem. I don’t have any removable, external, card or stick, etc., (???). As a layperson, I don’t want to open the laptop case and risk causing additional problems. That is to say, I don’t know whether the other “solutions” mentioned in the 2007 thread would work.

The battery is on its way out, but it does still take a charge, and I can also use the power cord. So, at first glance, at least from a layperson’s perspective, it doesn’t seem that the battery is the cause of the keyboard problem.