I have a GFCI Receptacle is my main bathroom that is not working at all it has 1 black wire 1 white wire and a ground, I have the same outlet in my other bathroom and it works fine it has 2 black wires 1 white wire and a ground, I was wondering if the lack of a black wire is my problem or can it be wired without.

Are these outlets on the same circuit? The non working GFI may have just gone bad. They do that. There may be some other problem. I can't imagine the working GFI having 2 black wires and only one white. It could be that the non working GFI is wired from the working GFI and something is wrong at the working GFI location. Check again for a second white wire.

Could be that the second black wire is going to another receptacle in the circuit to provide GFCI protection there too. You'd have to tell us how the two black wires are connected to the GFCI to know for sure.

Yes Bob, but you would still have to have a second white. Right now I'm guessing that it's there but has become disconnected.