how do I turn off Voice Over?

click the home button 3 times...

if that doesnt work, i believe you can change that through iTunes under the general tab...

through the iPhone, Settings>Accessability>Voice Over

Go to Settings>General>Accessibility>VoiceOver to turn it off. With VoiceOver on you'll have to flick the screen with three fingers to scroll. You'll also have to tap and item once on the screen to select it, then double-tap it to activate it. (Example: to open Settings, tap Settings once to select it, the double-tap it to open it.)

My screen is black buy go into accessibility and turn voice to off

Try resetting your phone by holding the on/off and home buttons at the same time until your see the Apple logo, then releasing.

does it work on the iphone 4

Does what work? Are you trying to turn off VoiceOver? If so, to do this on the phone, follow this exactly as written:

1. 1. Press Home.
2. Tap Settings. Then double-tap Settings.
3. Tap General. Then double-tap General.
4. Use three fingers on the screen to scroll to Accessibility.
5. Tap Accessibility. Then double-tap Accessibility.
6. Tap VoiceOver. Then double-tap VoiceOver.
7. Tap "On" next to VoiceOver. Then double-tap "On" to turn it off.

Otherwise, you can connect your phone to your computer and turn it off using iTunes as described here: http://support.apple.com/kb/HT3577.