iPad or iPhone doesn't appear in iTunes

[guest]

Situation: iPad or iPhone doesn't appear in iTunes or you can't sync iPad and iPhone to a computer.

Resolution:
1.Disconnect other USB devices from your computer and connect iPad to a different USB 2.0 port on your computer (not on your keyboard).
2.Turn iPad off and turn it on again. Press and hold the Sleep/Wake button on top of iPad for a few seconds, until a red slider appears. Then slide the slider. Then press and hold the Sleep/Wake button until the Apple logo appears.
3.Restart your computer. Then reconnect iPad to your computer.
4.Download and install (or reinstall) the latest version of iTunes.