Did you try to press CTRL key once again to check if you can disable this?
To be honest it’s not easy to say what could affect the keyboard functionality but it could be possible that the keyboard starts to malfunctions…
In such case it would be enough to replace the keyboard.
But the point is that this is only an assumption.
Maybe it’s better to check the old keyboard firstly (this is a job for technician) before purchasing a new one.
You can make a short diagnostic yourself: Connect an external keyboard and check what happens. If the external keyboard works properly and you don’t have any problems it seems to be the internal keyboard only and it would be enough to replace this part only.