If you can't connect to a cellular network, make sure cellular data is on in Settings > Cellular. Restart your phone Check Carrier settings Try removing the sim card and re-inserting it. Here is what the part looks like scroll down and you will see the antenna. iPhone 6 cellular antenna location/replacement Sherri
Did you let the phone completely dry out, I would let it dry at least a few days. Make sure all cables are in correctly especially if you replaced the screen. Make sure you have the latest Itunes installed on the computer you are using. Try resetting the sim card. If that doesn't help call Apple or your phone carrier for replacement. Sherri
You can try this... Remove the SIM card, plug the phone into the computer, and performing the "Restore / Restore & Update" now without the SIM, which worked fine and then slipped the SIM back in the phone and started using it. Sherri
Reboot the computer without the headphone jacks. Sometimes you can reset the power. Remove battery and unplug electric cord, Hold down the power button for 30 seconds. Reboot, if that doesn't work - Go to device manager and uninstall sound devices reboot.
My Granddaughter left hers out in the snow for 2 months I opened it let it dry and it works. Then she dropped it in the toilet....let it dry and it works. Turn it off and let it dry 2-3 days then try it. Sherri