Beginner to Arduino here, just bought my board (Uno) yesterday, and it worked fine for a while. I was able to control a stepper motor with it before it crashed. Currently, my board cannot store my code, although I haven't gotten any error messages from my IDE or my computer. Pins 0-3 are always on, and pins 4-13 are always off, regardless of what my program says. I'm not sure if it can't store anything, or if it's still running the last program I put onto it, which was a simple stepper motor controller using pins 0-3 (which worked perfectly a few hours ago).
The stepper motor controller was a simple circuit that used a ULN2003A transistor array to control a 5-wire stepper motor (PM55L-048, unsure if bi- or unipolar). It worked fine. Then I attempted to control a 4-wire stepper (Sanyo B00324, probably bipolar), both with and without the transistor array (connected directly to the arduino). I played around the wiring, since I was unsure of the configuration. The motor never spun, but kept vibrating. After about an hour of tinkering, I gave up, and went back to playing with the 5-wire stepper. My circuit/code setup no longer worked, and the pins are now stuck in the state described above. I have tried and failed to reprogram the pins.
I will gladly provide any additional details. Any help is appreciated.
EDIT: Should probably include my circuit as well. I followed this one, but didn't use the pot: