IPhone can't start - Apple iPhone 3G

If you tend to restore iPhone to factory settings, there are two methods for you.

Restoring iPhone to Factory Settings with iTunes

iTunes enables users to back up data to iTunes and restore iPhone to factory settings. Before you start restoring iPhone to factory settings, please note that you need to install the latest version of iTunes on your PC or MAC. Then go to Settings > iCloud to turn off Find My iPhone. Now, the detailed restoring steps are as follows.
1. Plug iPhone into the computer with the USB cable. The iTunes on your computer will automatically launch. If not, double-click the icon to start it.
2. Click the name of your iPhone at the upper right corner of iTunes, and then the information of your iPhone will be shown. Click the "Restore iPhone" button in the window to start.
3. iTunes will ask whether you want to back up iPhone before restoring. You'd better choose "Yes" for the reset will erase the contents in your iPhone. Then iTunes will start restoring your iPhone to factory settings.

3. Click Restore again to confirm. Then iTunes erases your iPhone and installs the latest iOS or iPod software. After you restore your iPhone to factory settings, it will restart. Now you can set it up as new.

If this solution won't work, follow this post. How Do I Restore My iPhone to Factory Settings

Check youtube.

It's quite easy. You can resort to iTunes to reach this aim. Just follow below steps.

iTunes enables you to restore iPhone 6 Plus to factory settings. Before you start restoring iPhone to factory settings, please note that you need to install the latest version of iTunes on your PC or MAC. Then go to Settings > iCloud to turn off Find My iPhone. Now, you can factory reset your iPhone 6 Plus with iTunes as follows.
1. Plug iPhone 6 Plus into the computer with the USB cable. The iTunes on your computer will automatically launch. If not, double-click the icon to start it.
2. Click the name of your iPhone 6 Plus at the upper right corner of iTunes, and then the information of your iPhone 6 Plus will be shown. Click the "Restore iPhone" button in the window to start.
3. iTunes will ask whether you want to back up iPhone 6 Plus before restoring. You'd better choose "Yes" for the reset will erase the contents in your iPhone 6 Plus. Then iTunes will start restoring your iPhone 6 Plus to factory settings.

3. Click Restore again to confirm. Then iTunes erases your iPhone 6 Plus and installs the latest iOS software. After you restore your iPhone 6 Plus to factory settings, it will restart. Now you can set it up as new.


For more methods, check: How to Restore iPhone 6 Plus to Factory Settings

Reset iPhone 5. Reset iPhone 5: Press and hold the On/Off Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears.

If you want to reset iPhone data settings, there are several different ways you to follow. I will show you one of them.

iTunes enables you to restore iPhone 6 Plus to factory settings. Before you start restoring iPhone to factory settings, please note that you need to install the latest version of iTunes on your PC or MAC. Then go to Settings > iCloud to turn off Find My iPhone. Now, you can factory reset your iPhone 6 Plus with iTunes as follows.
1. Plug iPhone 6 Plus into the computer with the USB cable. The iTunes on your computer will automatically launch. If not, double-click the icon to start it.
2. Click the name of your iPhone 6 Plus at the upper right corner of iTunes, and then the information of your iPhone 6 Plus will be shown. Click the "Restore iPhone" button in the window to start.
3. iTunes will ask whether you want to back up iPhone 6 Plus before restoring. You'd better choose "Yes" for the reset will erase the contents in your iPhone 6 Plus. Then iTunes will start restoring your iPhone 6 Plus to factory settings.

3. Click Restore again to confirm. Then iTunes erases your iPhone 6 Plus and installs the latest iOS software. After you restore your iPhone 6 Plus to factory settings, it will restart. Now you can set it up as new.


For more methods, check: How to Restore iPhone to Factory Settings

Hello

More resets:
Try This:
1. Remove Sim Card
2. Hold in 'Home' button and 'On/Off' button together until Apple logo appears
3. Replace Sim Card
4. Hold in 'Home' button and 'On/Off' button together until normal phone screen appears.


Also, Try this:
1.) Shut down the iPhone 3G.
2.) Start up iTunes
3.) Hold down HOME button on the iPhone 3G
4.) While keeping the HOME button depressed, plug in the Sync cable
5.) A message will pop up to ask if you want to reset.
6.) Just click YES and the reset process should start.
Factory Reset iPhone Do it the Right Way Any Generation

You can resort to iTunes to reset your iPhone with ease. Just follow below detailed steps.

iTunes enables you to restore iPhone 6 Plus to factory settings. Before you start restoring iPhone to factory settings, please note that you need to install the latest version of iTunes on your PC or MAC. Then go to Settings > iCloud to turn off Find My iPhone. Now, you can factory reset your iPhone 6 Plus with iTunes as follows.
1. Plug iPhone 6 Plus into the computer with the USB cable. The iTunes on your computer will automatically launch. If not, double-click the icon to start it.
2. Click the name of your iPhone 6 Plus at the upper right corner of iTunes, and then the information of your iPhone 6 Plus will be shown. Click the "Restore iPhone" button in the window to start.
3. iTunes will ask whether you want to back up iPhone 6 Plus before restoring. You'd better choose "Yes" for the reset will erase the contents in your iPhone 6 Plus. Then iTunes will start restoring your iPhone 6 Plus to factory settings.

3. Click Restore again to confirm. Then iTunes erases your iPhone 6 Plus and installs the latest iOS software. After you restore your iPhone 6 Plus to factory settings, it will restart. Now you can set it up as new.


For more details, check: How to Restore iPhone 6 Plus to Factory Settings