If you recently updated to the iPhone 3.0 firmware you may find that you can’t sync your iPhone in Windows (reports coming in from Windows 7, Vista and XP) without receiving an error. The sync is automatic after the update, and the lame part is that when it fails it will make all your media invisible to you in the iPod app.
Luckily there is a solution to this fail other than restoring from a backup (lengthy) or just throwing your Jesus Phone away.
HOWTO: Fix iPhone sync error 13019
Heres how to fix.
Unsync your music/videos or whatever isnt going onto your iphone/itouch by plugging in your device and unchecking the sync box within each multimedia tab then click apply. Let the device sync then once completed reconnect your device check all your sync tabs that you want and sync again. This should resolve the problems and sync your files.
It should only be your music and videos and some podcast that dont sync at the start but this description should fix the error 13019.