Phone loses network out of the blue

Yesterday I noticed I only had 1 bar. I restarted my phone and was able to use it.  By 10am, I had a circle with a line through it. My children who were out of the house at the time, were experiencing the same. I was not able to make a phone call or text or use the internet unless connected to the wifi. My phone(s) were working just fine before this. Customer service guided me to a network reset... it's the next morning and I still don't have network service. Even on wifi, I cannot download apps from the playstore ad the message is I'm not on a network.