Please i can't send SMS using my line 0597672598 i need help

I need help retrieving an important message sent on my MTN line. I cannot access the sms, but I can still use my line for WhatsApp messages. Please advise me on what to do. I...

Though, it's a new phone.I've made all necessary changes and settings but it's still not working.

I can't check my balance or even use the data I just got because my mtn line keeps sending me the same massage that my line has been temporarily blocked, please I need a way to...