Typically, when you have a GFCI, there are outlets "downstream" that are fed from the GFCI. Any of those downstream outlets can trip the GFCI outlet. If you pull the GFCI, you will see that it is labeled with "LINE" and "LOAD" attachment screws. If you disconnect the LOAD wires, you may be able to reset the breaker and/or the GFCI. If that works, your problem is with one of the downstream outlets. Only solution is to pull those outlets, one at a time, and disconnect them from the circuit and then retest the GFCI reset. You may find the problem by visual examination while doing this. (As in wet, or corroded wire on the offending outlet)