My wife had a 4s I have a 5s and she switched to a Samsung, now we cannot send texts

I have a 5s my wife had a 4s, she just switched to a Galaxy, and we cannot text because the 5s still believes her number is 4s. I deleted her as a contacts turned off iMessage then back on, and nothing. I have tons of contacts with iPhones and tons with Android and iMessage can distinguish between all of them, but with her new phone it cannot distinguish. Any help would be appreciated.

Erci