I have a chandelier with 2 black wires and a ground wire and I have to connect it to 1 black wire, 1 white wire, and a ground. What do I do?

Is one of the black wires coming from the chandelier ribbed? (Has a texture to it while the other is smooth)? If so, the ribbed one is your neutral, which will connect to the white wire in the ceiling box. If not, you can usually just connect one black chandelier wire to the black wire in the ceiling, and connect the other black chandelier wire to the white wire in the ceiling box. However, this could switch the hot and neutrals in the chandelier, and I'm not really sure if this is permissible, so I will wait for someone else to answer. Either way, The two ground wires will be connected together.

Yes, ribbed wire is neutral. All new wiring used for this purpose is marked.