usb comm not working !!!

Hey, this is my first time in the forum. I bought my Arduino Uno R3 for a mini project im doing in my college. it worked fine for some time but not im not being able to upload any codes to the board. the board is not even being detected in my laptop or any other computer. when powered the amega16u2 gets heated up fast. did i damage that ic? im not being able to figure out the reason. i had powered the arduino by converting a 12v to 9v using a voltage regulator to the VIN pin. Could that be the reason ? please do help. Thank you.

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Can you tell me what the reason might be ? I dont want to burn any other boards.
Thank You

How can WE tell you what's the problem if YOU did something with that chip ?

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