I have a golden-age Batman Statue like this one, but the ears broke off.
There is a wire in one ear that I think was used as support. I'm not sure of the material but I assume it's resin. Does anyone have any idea on what materials I have to resculpt the ears?
Tamiya Epoxy Putty works for me. It's a 2 part putty where you have to mix part A and B and it has no trouble sticking to resin. Generally, available at most hobby stores that sell Tamiya products. Probably a good idea to wear nitrile gloves.
Yes, as TazMan already said, Epoxy Putty is the best for this. Once you get to painting, it will be difficult finding the exact color of black though, if you still have the ears, you can use them to test paint until you find the correct shade.