Fb msgs and texts not coming in or going out between my galaxy 4 and his iPhone 6 (Plus ?)

A

AC Question

Messages were going through fine for months... Both texts and Facebook messenger... Then all of a sudden they wouldn't go through to my phone from his, or to his from mine. I have a Samsung Galaxy 4 and he has an iPhone 6 (not sure if plus)... So frustrating! Sometimes snap chat won't even go through... Please help!