Help with fried arduino UNO (With Image)

I was connecting a stepper motor to a SN7544 Hbridge and to the arduino, I had already plugged the ground from the 12V power supply to the breadboard and before I finished connecting the stepper, the positive wire from the PS touched the positive power buss on the breadboard so it sent 12V to the pins that support only 5V on the Hbridge so it instantly fried and also fried the next component in the Arduino, circled in red (Thats not my actual Arduino, is just to clarify which part):

I have tried some simple circuits with pushbuttons and LEDS and it seems everything is working, the only problem is that the same part in the red circle gets really really hot when I connect the arduino to the computer, so iam afraid I fry something else with continous use without reparation. Whats that part? I think its a 3.3V regulator but iam not sure. Pls help me fix my Arduino ;(

If you look at http://arduino.cc/en/uploads/Main/arduino-uno-schematic.pdf there is only one five pin component there and it transforms the USB Vcc to 3.3V. It is an LP2985-33DBVR. If you have a multimeter, you can check the voltages.

It is entirely possible that more components are fried, like the op-amp LM3580, as it also connects to 3.3V.

Obviously this doesn't help you now... but you should never change connections while powered! Even trivial changes can result in unexpected damage...

Yaa, I know, it was an accident :frowning: