My central locking suddenly stoppled to work. I have to lock and unlock all the doors one by one. Do You have any suggestions, what to do and how this can be fixed "DYI"?

 

Is there a recall on the window switch in your country? Getting that replaced seemed (fingers crossed) to clear up an issue for me. Otherwise I would be inclined to think possibly one of your lock actuators went out and is preventing them all from functioning properly... not sure of an easy test to determine which one though I am sorry.

Check fuses first!!! Or battery in remote?

 

Sometimes a damaged driver's door switch (the one on the B pillar, behind the door) can prevent the central locking system from working. The seat belt buckle gets caught...then the car thinks a door is open.

Often the damage remains hidden behind the rubber cover.

 

I had the same problem on my 2010 Fit. It was the drivers side power lock actuator. It's not too difficult to remove (a few good videos on youtube) and the part was $175 (us). Did the swap out and it's all fixed. Hope this helps.