I lost Global Catalog

I lost my global Catalog on a windows 2000 DC.
I have tried to uncheck the Global Catalog in Sites and Services NTDS properties and rebooting on the DC, then rechecking and rebooting in the hope it would recreate one. It did not. I created the new reg key IgnoreGCFailure and it worked as far as my users logging in and having rights, but I want it back. Help….