I guess you have got this screen since you are visiting this tutorial !
 

Well look no further ! This is the tutorial for you ! And probably someone else too !
What this will do is that it will reset it to the time that you last hooked up your device to your computer !

First !  Hold down power button and turn of your device

Second !  Now hold down the HOME button as you do plug in the charcing cable
Third !Get your device synced with apple’s software iTunes. It will tell you that you need a system restore.
Click ok !