I have tested all my GPIO pins in the past, and I know they all worked as outputs. Today I was using pins 11,13 and 15 (Board numbering), and they were all working fine, but suddenly pin 15 stopped working. Now after disconnecting everything I can't even light an LED up with pin 15 any more, but with the same wire and same LED and same resistor I can light it with pins 11 and 13.
So it looks like whatever I did, I've unfortunately fried pin 15. I guess I'm lucky the other pins escaped. Has this happened to anyone else, and is this damage maybe fixable (some kind of fuse can be reset maybe?) or is it probably permanent?