I had attatched a GSM module to my arduino Uno board. The power had been switched on. The GSM 5V pin was connected to my board. I was still midway with my work so for some reason I gave an external power supply to my GSM module. Now smoke started coming out of my Uno board and a burning smell came from it. I immediately switched off the power supply. But now I am unable to burn sketches to my Arduino. It is showing error: Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions. On opening the serial monitor it says: Board at COM3 not detected.
Link from wher I bought the GSM module: http://www.ebay.in/itm/GSM-Module-SIM800-Quadband-better-than-SIM-900-or-SIM900A-Modem-with-SMA-Antenna-/252053758680?hash=item3aaf9322d8