Traffic jams blew - no electricity in almost the entire apartment

I apologize in advance for the lack of professional vocabulary, but I am completely unfamiliar with electricity .

So: in the apartment only the computer, router, lamp, router, desk lamp and one overhead light in the room were on. I got up from the computer, I go to the bathroom and suddenly: boom !, the light went out with a bang, I thought that I would come down to a heart attack, because it was really loud. Everything turned off, including the computer. I immediately looked into the 'such' box with traffic jams above the front door, and the first and eight switches were tilted downwards, so I flipped them up. And the light came back - partially.
It is in sockets near the floor (throughout the apartment).
And the overhead lights don't work anywhere, in any room. The light in the hood and the refrigerator do not work either - I have no idea how the refrigerator is connected, at what height the socket is located, I will not move it myself.

What could be the cause of what happened?

Maybe the extension cord to which the computer, speakers and lamp are connected is defective? But it didn't burn, so I can type from my computer now.

Or maybe it was due to too heavy a load? But I do not know by what miracle, because the norm is 3 overhead lights, 2 laptops, 1 standard computer, dishwasher, fridge, washing machine and somehow nothing happened then. And now a third of it only worked, and yet the light went out.

I remembered that in the last few months my traffic jams had been blown off several times. But I don't remember which ones. And then, after turning on these traffic jams, the light came back everywhere. And now 'zonk' doesn't work for the most part.

Please help, because I have a full fridge and a freezer and I'm afraid that this will melt by the morning and I will have a flood on the kitchen floor from the freezer, because I think this melted ice will start flowing out.

Thank you in advance for your help.

Go to the corridor and activate the pre-meter protection.

I went out into the hall and there is something like a box, unfortunately locked. I don't know where the key comes from in such situations, what do people usually do in such situations?

And additional information: there are apartment numbers on this box and such transparent glasses, and only under my glass there is such a red light. Maybe it means something, I don't know really, I'm writing just in case.

Thanks a lot and please give me some more tips

Call the electrician who looks after the building.

Ok thanks a lot again

Do you have three phase power? (eg for an induction cooker?) If so, then most likely there is no phase 1 on the power supply. The red light on the meter may mean just that. It is necessary to gain access to the pre-meter protection and check that it is not turned off. Since the box is locked, the owner of the house (caretaker), administrator or electrician, mentioned by Col. Łukasz, may also have the key.

venetia wrote:

I remembered that in the last few months my traffic jams had been blown off several times.

This is not a normal symptom. After removing the failure, it is worthwhile that a good electrician review the installation for frequent disabling of security devices.