White apple in middle of black screen of iphone3g

If you mean to restart the phone, just press Power Button and the Home Button together until you see an Apple Logo in white on the Screen

Now, if you are looking to apply in full a Factory Reset, go to Settings, then General, scroll down and tap on Reset, then choose the option for Erase All Content and Settings. Remember your iCloud information since it will be asked to you. Anything, let me know.

Just to be clear a "hard reset" will remove everything and restore your iPhone to its factory settings.

Settings - General - Reset
Here you will have various options, the main ones being:

• Reset All Settings
• Reset Network Settings
• Erase All content and Settings
  • Selecting "Erase All Content and Settings" is what constitutes a Hard Reset. Your phone will ask you to enter your passcode, and will then ask to confirm.

Ok, I'm using my iphone 4 running 7.1.0 as my guide on this one, so I must not be using all the correct headings, but this should be close. Go to "settings->general->reset->Erase all content and settings". That should erase all personal data, contacts, songs, photos, etc... And reset all of the settings to factory default. If you think you may want to reverse this, or if you're planning on upgrading to a newer generation of iPhone and want to transfer your data then be sure you sync your phone with iTunes before doing this. Let me know if that does not work, there is another way to do it but it will require you to update to the latests version of iOS that your device can run, which will erase your jailbreak if you've installed one (not to be confused with re-lock your phone, if you paid to get your phone factory unlocked, and that does not mean a sim interposer, your phone should remain unlocked, no matter if you update iOS).

1. Tap the Settings app on your homescreen.
2. Scroll down to the General menu. Tap it.
3. Scroll all the way to the bottom and tap the Reset menu.
4. On this screen, you'll be presented with a number of reset options, ranging from just resetting the iPhone's settings to resetting its dictionary or homescreen layout. There's nothing specifically labeled "factory reset"; the option you want is called Erase All Content and Settings. If you're sure that's what you want to do, tap that.
5. If you have a passcode set on your phone, you'll be prompted to enter it here. If you don't have one (even though you should!), skip to the next step.
6. A warning pops up to make sure you understand that if you proceed you'll be erasing all music, other media, data, and settings. If that's not what you want to do, tap Cancel. Otherwise, tap Erase iPhone to continue.
7. It generally takes a minute or two to delete everything from the iPhone, but when the process is done, you'll have a brand-new, pristine (at least from a software perspective) iPhone ready for whatever your next step is.

Reset iPhone to Factory Defaults.

1. Begin the process, if possible, by backing up the data on your iPhone 4. Do this by syncing the phone (each time you sync, it creates a backup). This lets you save all your data and settings to restore to the phone after the reset.
2. When that's done, locate the Settings app on your iPhone homescreen. If you've rearranged your apps, locate it wherever you put it. Tap the icon.
3. Scroll down to the General menu. Tap it.
4. Scroll all the way to the bottom to the Reset menu. Tap it.
5. On this screen, you'll be presented with a number of reset options, ranging from just resetting all the iPhone 4's settings to resetting its dictionary or homescreen layout. The factory reset option is Erase All Content and Settings. If you're sure you want to factory reset your iPhone 4, tap it.
6. You'll see a warning reminding you that you'll be erasing all music, other media, data, and settings if you do this. If that's not what you want to do, tap Cancel. Otherwise, tap Erase iPhone.
7. It will generally take a minute or two to factory reset the iPhone, but when the process is done, you'll have a brand-new, pristine iPhone ready for whatever your next step is.

You need to factory reset the iPhone. it is a simple process



Begin the process, if possible, by backing up the data on your iPhone 4. Do this by syncing the phone (each time you sync, it creates a backup). This lets you save all your data and settings to restore to the phone after the reset.
When that's done, locate the Settings app on your iPhone homescreen. If you've rearranged your apps, locate it wherever you put it. Tap the icon.
Scroll down to the General menu. Tap it.
Scroll all the way to the bottom to the Reset menu. Tap it.
On this screen, you'll be presented with a number of reset options, ranging from just resetting all the iPhone 4's settings to resetting its dictionary or homescreen layout. The factory reset option is Erase All Content and Settings. If you're sure you want to factory reset your iPhone 4, tap it.
You'll see a warning reminding you that you'll be erasing all music, other media, data, and settings if you do this. If that's not what you want to do, tap Cancel. Otherwise, tap Erase iPhone.
It will generally take a minute or two to factory reset the iPhone, but when the process is done, you'll have a brand-new, pristine iPhone ready for whatever your next step is.

Formatting an iPhone 3G will erase all the data on your phone, delete all your apps and reset your phone to factory settings. Formatting your phone is a good last resort if you're having software issues with your phone. Keep in mind that the format is permanent and any data irrecoverable.

INSTRUCTIONS:

1.Click the "Settings" icon.

2.Select "General."

3.Scroll to the bottom and select "Reset."

4.Select "Erase All Content and Settings." A warning message will display. Confirm your selection. The iPhone screen will turn off then show a "waiting" sign. After formatting is complete, the Apple logo will display and finally your formatted iPhone will reboot.

Read more: How to Format an iPhone 3G ' eHow.com http://www.ehow.com/how_7640130_format-iphone-3g.html#ixzz1WCkuLtuM

You bricked the iPhone follow this:
Hold the Power and Home button for 10 seconds Release the Power button, hold Home for 5 more seconds. Plug into iTunes

restore it in DFU mode !!