Currently Being ModeratedMay 15, 2013 6:23 AM (in response to Gaboum)
I was researching ways to troubleshoot the issue you are describing, and found some relevant troubleshooting steps that may help resolve the issue without service.
From our iPhone Troubleshooting Assistant found here: http://www.apple.com/support/iphone/assistant/phone/#section_1, I would recommend sections 1, 3, and 5.
On section 3, it talks about closing an app, but I would like you to close ALL the apps that are open.
Here is section 1 to get you started.
To restart iPhone, first turn iPhone off by pressing and holding the Sleep/Wake button until a red slider appears. Slide your finger across the slider and iPhone will turn off after a few moments.
Next, turn iPhone on by pressing and holding the Sleep/Wake button until the Apple logo appears.
Is iPhone not responding? To reset iPhone, press and hold the Sleep/Wake button and the Home button at the same time for at least 10 seconds, until the Apple logo appears.
If your device does not turn on or displays a red battery icon, try recharging next.
All the best,