HT4623: Update your iPhone, iPad, or iPod touchLearn about Update your iPhone, iPad, or iPod touch
Currently Being ModeratedJan 18, 2013 7:06 PM (in response to sinos12)
You can try to reset it by holding the power and home buttons at the same time until you see the Apple logo, then releasing but it may not work at this point. If not, you'll have to force it into recovery mode and restore it, as explained here: http://support.apple.com/kb/ht1808. If you have an existing backup you will be given the option to restore to this backup at the end of the restore process.