Message app frozen

Hi, I have a problem with my iPhone, I have iOS 11.2 on iPhone SE and i don't know for how long maybe 2 weeks and I had iOS 11.1 before my messages app is just frozen and blank, it won't load and i can't send or receive text messages. Also, in settings when i click on messages it freezes for a while and then wants me to sign in with my apple ID, and everytime I do so, it says "iMessage Activation - unable to contact the iMessage server. Try again. I tried to reset settings, restart phone, and even factory reset so I had my phone as new.. Still doesn't work..I don't know what to do, maybe wait for another update ? It's really annoying because I need messages.