Arduino Uno not detected by computer

I have 2 arduino UNOs. Both of them are working fine until this morning. Suddenly one of them isnt detected by the pc. When i plug in the USB cable, there is no USB device connected sound. I have tried changing USB cables and it is not the issue here. The green LED for power is lighted on and the the led 13 is blinked when i plug in the USB so i suppose the bootloader is fine. Help would be greatly appreciated.

Bump, same problem.

Same here, if you find a solution, please tell us

same problem with me. :(