Macbook keys "4 $", "F4" and "} ]" have just stopped working. Any help?

Hi everyone,

3 keys on my Macbook Air have just stopped working and I have no idea why.

I didn't spill anything on them, nor I have damaged my Mac. It is sitting on the same table for a long time.

The keys that don't work are "4 $", "F4" and "} ]"

I have opened the keys and there is no dust or anything there that got stuck bellow.

Anyone knows if there is some way to solve this issue before I take it to the service?

Could it be some software issue?