How do I fix my iPhone if it won't make or receive calls or text messages?

If your iPhone won't make or receive calls or text messages, there are any number of variables that could be at play. The most common problem is that you could be in an area with no cellular coverage or a weak cellular signal.

Apple's own site has a very helpful walkthrough that includes checking the signal, resetting the network settings, repositioning the SIM card, checking with the carrier, and finally as a last resort, restoring the iPhone. Please note that restoring the iPhone will erase all data. Be sure that you have recently backed up your iPhone before restoring it.

How do I get my iPhone to connect to the Internet?

In general, the iPhone should automatically connect to the Internet when Safari or an Internet-connected app is launched. Apple's own support site has a helpful document that explains the details of the procedure, but essentially the iPhone will first try to connect over the last Wi-Fi network used. If the last used Wi-Fi network is unavailable, it will provide a list of available Wi-Fi networks and if you don't select one, it will connect over an available EDGE, 3G, or 4G cellular network.

How do I fix my iPhone if it won't connect to the Internet? 3G or 4G won't work? Wi-Fi won't work? It won't load a website?

Odds are good that the issue is not with the iPhone itself, but rather an issue with the iPhone settings or the network. Apple provides a helpful document to walkthrough common wireless networking problems that one may encounter with the iPhone.

If none of Apple's suggestions solve the issue and you can't get your iPhone to connect to the Internet at multiple locations, try the Apple recommended "recharge, restart and reset, update and restore" procedure for good measure one last time as well. If it still won't work, the iPhone could be physically damaged and require service.

Also see: How do I send in my iPhone for service?