Why cant i press my mobile network settings on my lg v20

So i decided to change the network settings on my lg v20 to lte but then out of no where my service just stopped working and then i changed it back to the orginal settings and i still did not get a connection and now i cant even press the mobile network beacause its locked

I have the Verizon V20, and I have to leave mine set to global to maintain service.

Thank you i will try that

I have an unlocked US Cellular V20 that I'm using on AT&T. I also use Global.