If an iPhone is locked you cannot sync it with iTunes. If you want to turn it on you need to plug in your passcode... If your display is broken and the digitizer still works (touch), This might work... >Connect the iPhone to a Mac. >Open Quicktime > File > New Movie recoding > There will be an arrow next to the record button pointing downward which gives you the option to select the iPhone screen. This should put the screen on the Mac and you can guess where the numbers are based on that and type in the passcode. You can also be sure it's the screen that's the issue.