U J M not Working, but Mouse Keys is disabled

One year ago I started to have problem with my keyboard. One day it simply would'nt work. I'm talking about U,J,M, 7 and some others.

After a lot of research I found that it was related to Mouse Key and some accessibility feature. Reset SMC, double check accessibility presets...

Sometimes the keyboard would work perfectly ok. Sometimes not. That made me thought that it was not hardware but software related. No spills on my laptop. NEVER.

One day it totally stops working (still talking about the same letters). It was one year ago or so.

Today, I don't know why it suddenly reworked. For ø`=+/ sake !!! I made my grief and you come back to life ?!

Ok, was happy, but that didn't last long.

It's broken again, and as you read me I'm typing my U and my 7 with an external keyboard.

I don't know if anybody can help me on this but I'd appriciate a lot !

My little sidekick of a laptop is nearly 10 years old, so I forgive him anyway.