3G disappeared from iPhone after updating to iOS 8?

I had this happen on my iPad2. I installed iOS 8, and my 3G data service disappeared. (In fact, it showed "No Service" in the upper left-hand corner, instead.) It wasn't until I did the power-down-reset that it came back. I share how to do that reset below, but first, there's one thing you should do that will help the chances of getting your service back.

Double-click on your home button to have your iPhone display all the apps you currently have open. Then, close each one down. You do that by swiping to the left to get the first app. Then, put your finger on the reduced image of your app screen and swipe up. That closes the app down, and frees up your memory. The next app that is open will, now, show. Do this until no more apps are open and only the reduced image of your home screen shows. Note: this does NOT delete the app. It only shuts it down, which again frees up your temporary memory but also processing speed. (More temporary memory available = better performance. You can get to a point where you're using all your memory, and then, your phone & apps start acting wonky or crash. But I digress.)

After you've shut down all apps now, come back to your home screen. Next, press your home button and power button at the same time AND HOLD THEM DOWN TOGETHER. KEEP HOLDING. You will see the power down screen asking you to swipe to power down. Nope, keep holding those buttons. Your will see the screen go black. Now, the Apple icon shows in the middle of your screen. KEEP HOLDING those two buttons! When the Apple icon disappears, you may finally let go. (This process only takes a few seconds, but we're not normally used to holding a button down on any of our devices for this long. That's why I put the extra emphasis by using caps.)

So, your iPhone is shutdown. Grab a watch and wait a minimum of 30 seconds. Why? B/c certain pieces on the motherboard of your device need that long (sometimes up to 60 seconds) to discharge the remaining electricity in them. You want it to fully discharge in order to let something stuck in memory to be released ("forgotten").

When 30-60 seconds have passed, you may restart your iPhone. It might take a tad longer to start up. Be patient. Your connection to your cell service should come back. Mine did on my iPad 2.

Hope that helps!

iOS 8 takes up a ton of gigabytes!!! its like 5 or something