My screen frozen due to icloud alert regarding delayed back-up.

I get the alert meaagse from my Ipad2 : This iPhone hasn’t been backed up in 2 weeks. Backups happen when this iPhone is plugged in, locked, and connected to Wi-Fi. Although I apply the suggested resolution; I still can not get the back-up started; and my screen is frozen and does not accept any commands ( I can not tap on any other icon ) . Pls help. Thnak you in advance .Kursat