See attached picture. I am not sure if the title is correct. The door bell button (the plastic cover area) broke. Can anyone tell where can I buy this exact doorbell?
I would doubt it that you will find the exact replacement.
All doorbells that I am aware of, are wired pretty much the same, 2 wires, doesn't matter which screw it goes to. You will be able to find a doorbell that may fit the same drilled holes, that chance is better than finding the exact same doorbell.
Any big box store, or local hardware store will have a selection in stock.
I don't know where you live of course but I used to live in a city that had an architectural salvage place where you could go browse and find old things for your house. I found an old window sash and thus saved myself the expense of having one custom made.
It might be worth a search online to find one nearest you. These tend to be places where a lot of browsing is required. You could very well need to sift through many boxes of old parts for hours to find the right thing. Still, it's one option.