List all the wires and their colors.
It sounds like a metal halide to me, which usually have 4 or 5 wires - white, black, two of the same color (usually red) and optionally a ground wire, green or bare.
Black is hot to the line
White is neutral to the line
The two same colored wires go to the lamp, any polarity
Ground goes both to the metal reflector and the line ground, or if the ground is not present, the case of the ballast should be connected as such.