after screen replacement, why can't I facetime and pics/songs gone?

Hello all, after I did a screen/digitizer replacement on the Iphone 6S Plus, why can't I facetime? Also all of my pictures and songs are gone. I am not new to screen replacements, I have done about a dozen for myself and friends. However, the Ifixit instructions for the first time, I have seen, said to unhook the battery connector. I did that and I feel this is a reason why I can't facetime and my pictures/songs have been deleted. I didn't do a system restore either, I didn't think I should have to do that after a screen swap. Any help would be greatly appreciated. Thank you!!