Computer does not recognize the board at ALL!!!

So basically my problem goes way back!!

A few years ago I bought from e-bay a kit that contained the arduino uno r3 itself and some other things for a variety of projects. At this point I have to say that my board is not an original one( I realized that after I got my board). Since I was a very beginner I downloaded the software and plugged my board into the computer. I think(but I am not 100% sure) that even the first time I plugged the board into the PC it did not tried to find any drivers. I had no idea about that procedure so I just plugged it in, opened the environment and started experimenting. In the beginning I did not have a problem, but after a while every time I plugged the board, I had to wait for a couple of minutes for the PC to recognize the board. And suddenly after some time, it stopped recognizing the board completely. A friend told me that I might have burned something wrong in the chip , which I may have done by mistake, so I bought another chip( not board just the atmega chip) hoping it would solve the problem( I bought it from an original distributor of arduino this time).But then I plugged it in the PC and again nothing happened.Not a try to install the drivers and in the device manager the board isn't anywhere(neither below the Ports, nor the Unknown devices).

What may the problem is????

Thanks in advance!