Connecting the Arduino UNO

Hello!
So i’ve got a problem connecting my friends Arduino UNO on computer. My Arduino works perfectly fine. He told me that he could made some kind of short circuit and that the Arduino need to be re-programed. So is it posible?
thank for your answers!

grosleon91:
He told me that he could made some kind of short circuit and that the Arduino need to be re-programed.

Well, short circuit can kill Arduino.

Does PC do a sound when you connect Arduino to USB? Does it appears as unkown device?

No nothing at all...but samo LEDs on the board are turned on.

Have you checked that you have the right board selected in Tools > Board menu?
Have you checked that you have the right serial port selected in the Tools > Serial Port menu (e.g. COM3)?

Is this 'short circuit' another name for an external isp programmer?
And when you plug in the board into you computer what exactly happens with the L Led? Does it do a blink sequence? And if so the problem may lie somewhere else.

No it doesn't do blink sequance. The LEDs turn ON and stays ON. About the right port i don't have any problems because my Arduino board work perfectly fine.

By the looks of it, the board's bootloader is not functioning correctly. Here is a link on how to re-program the chip using another Arduino. http://arduino.cc/en/Tutorial/ArduinoISP

Hopefully this fixes it.

“LEDs” - does that include the Rx and Tx LEDs? Those are controlled by the USB/Serial interace.
If that part is dead too, putting a new bootloader on the '328P won’t help.