iPhone Messages Settings has no options

My husband recently left a job and they let him keep his iPhone 6. The company had had problems with iMessage, so all of the work phones had iMessage disabled. Now that it is a personal phone, we would like to turn it back on, but when you go into Settings -> Messages it is literally a blank screen. I assume they somehow disabled it so people couldn't turn iMessage back on themselves. Does anyone know how to get the options back?