Did I burnt my arduino

I bought an Arduino UNO R3 , It was my first time

Then , I plugged my 12v (1.5A) adopter , The board worked . Then I plugged my usb cable , I am a begginer I did not have any knowledge , So in total the supple from my port and supple of 12v adopter doubled the supply of the current which lead to burn a thing of my arduino i don't know what it is
Then I plugged USB adopter only the lights of pin 13 (orange light) and the ON light(Green Light) were on
Still My PC is not detecting it can someone help ?

here's a pic of burnt piece

The piece name is SOT - 753 ( 3.3 V Regulator)

Can anyone please help me ?
Will it work or I have to buy a new one ?

Is it original Arduino?
Normally, the board can be powered via barrel jack and at the same time connected to USB. There is a circuit which is switching automatically between power sources. You had to do something wrong if 3V3 regulator is burned (it is marked on picture).
This regulator is a part of circuit I am writing about.

Eventually, you can use it without this circuit but probably there is something else broken.
I think, it is possible to repair the board but some more advanced skills and tools are required.
I'm sad to say it but maybe you should buy a new one.

It is original arduino, I think the 12v adopter is too powerfull as when I plug them seperately , Via the USB the light are low , VIA the adopter the Lights of the arduino are too powerful

12V is not too much.

I removed that 3.3V regulator and the led still works like before

Look at the tech specs. There is 6-20V limit. Maybe the problem is in the adaptor you used. Better to check output voltage.
I cannot say if LED's light is low while it is on USB. It was built for 5V and USB has relatively accurate 5V.

I removed that 3.3V regulator and the led still works like before

You should replace the regulator. The L should blink 3 times at the reset but first the port should appear in PC.

Plenty Unos seem to have died when both 12V and USB were connected at the same time. Limit the voltage on the power jack to 9V.

Usually the 16U2 seems to die, not the 3.3V regulator (as far as I remember).