Arduino Uno Rev 3 not detected by windows 7

hi i have an arduino uno rev 3. All the drivers everything is properly installed in the computer. The board was working fine till yesterday and then suddenly the computer stops detecting it and i get a code 43 error. I have one more board of the same kind which is working perfectly fine on the same counter. The atmega chip isnt fried because i checked whether ground and vcc is shorted and it isnt. Please help!