My gum has just recently started turning black, is there any home remedies I can use to cure it?

No. See your Dentist for this. It may simply be hardened calculus (tarter) build-up under the gums that has turned dark and is making the gums appear black. OR, it could be something else, having to do with the gums themselves. Often we see systemic medical problems appear in the mouth. See your Dentist for examination, diagnosis and tx options. Good Luck.
See a dentist ASAP. Black gums can be a sign that you are at risk for or already have gum disease. This is a serious problem, which should be checked by a dentist. The good news is that this condition is curable. Call your dentist today!