PC is not detecting Arduino uno

Hello, I programed my arduino uno r3 on windows7 os to run a dc motor. I used a verified circuit with 2N2222 transistor and IN4007 diode and proper resistances. I used 3.3v arduino supply for a few seconds to power up the motor and the 9th digital pin to control the power. Since then, I am not being able to reset the Arduino or upload any new program as my pc is not detecting arduino uno. But when I connect Arduino with PC via USB the Arduino is getting power and the previous program is running fine.

I tried different cables. I also installed manually the device using the add hardware menu (tried with the Arduino uno driver) and it gave me the error: This device cannot start Code 10 error.

Is my arduino damaged or whether i can fix it somehow?
please help....

You probably fried the 3.3V regulator. I don't know how to fix it. Can you post a pic of your setup? (And also the motor, next to the Arduino).