arduino uno shorted.

Hello guys... I guess my Uno is shorted... I was trying to make connection without using registers.. And while the Arduino was connected to Pc, And I was powering my GPS module using Arduinos 5V.. Than I accidentally powered the Gps module with external power supply through the adapter.. And than the pin 13 LED stoped blinking.. Now the 13 pin LED doesn't work.. And arduino is not getting connected to the Pc.. How can I repair it.. Please give some suggestions..

Measure 5V pin and the 3.3V pin on the Power header. Look good? If not, the regulators may be gone. Is the 328P chip hot to the touch? If yes, it's dead and needs to be replaced. Pull the 328P out of the socket and try the Loopback test (at the top of this forum). Still no go? The USB/Serial adapter chip is shot.

If just the 328 is hot and everything else is ok, just replace the chip: http://www.dipmicro.com/store/CPU-ARD328P

Thanks for the reply.. But the serial port in arduino IDE is greyed out..