When that happens, you might see the "your phone is not registered on a network" on your screen, which means your SIM card can't connect to your wireless provider's network.

If you don't spot a connection in the status bar, try ejecting the SIM card tray and inspecting it and the SIM card for any damage. Reinsert it and reboot your phone to see if you have network ...

What happens when you reset network settings on mobile devices? When you reset the network settings on an Android phone, it puts everything network-related back to the default state.