Gniazdko elektryczne - gdzie podłączyć odłączony brązowy przewód?

Witam. Odłączył się brązowy kabel w

gniazdku. Gdzie go podłączyć?

I see more questions there
Why are there 4 wires in a triple connector?
Why is the PE wire not connected?
In this situation I always recommend reviewing the whole installation if there are already several doubts in one picture. In general, the socket was connected by someone who should not have done it.

I also see more questions.
E.g.: is this a socket with a protective (pin) pin, because it looks like one. If so, why isn't there also a PE wire to it.
The different number of L and N wires in these wago connectors, is also puzzling.
You can also see a yellow-green wire in the box, probably not connected to anything.
In view of the above, it is impossible to give a definite certain answer without verifying this installation, as it could be very dangerous.

No offence, but it's better to call an electrician, because, as the author of the topic, if you ask such questions, it shows that you don't have a clue, and in this case it's impossible to give a clear answer.
So it's unlikely that anyone here will undertake to tell you where to connect it without being able to verify this with a proper visual inspection/measurement, because they don't want to have you or anyone else on their conscience.

Rysio4001 wrote:

is this a socket with a protective stud (pin), because it looks like one.

Yes it is a socket with a protective pin. You can see the "Christmas tree" on it.