My GFI sparked and won't reset
To piggybak on what j187 said, the breaker may trip and it is still appears as if it is set...if you wiggle a little it may not feel TIGHT this indicates that it is tripped...as he said turn it off and then back on...
Also just as a note, in my house, out of 15 or so breakers, only a few were labeled correctly...I have since relabeled them but what a pain...if it comes to that, reset each breaker individually. Try the 20 AMP breakers first as these are probably kitchen or shop curcuits.
By the way...are there any other GFI's on that curcuit?
"What if the hokey pokey really IS what its all about."