iPhone not able to Sync. Stuck at Backing Up in iTunes

iTunes keep on stucking at Backing Up stage indefinitely?

You can try the following:
1) If you just want to sync, you can open up task manager and kill the backup process (Apple backup .exe I can't remember the exact process, just try to kill the one with backup), then the backup will skipped and you will proceed to sync.

2) If you want to do a backup, I assume your phone is jailbroken, disconnect your phone with iTunes, turn off your phone, enter safe mode, (Holding down Volume Up key while booting, keep holding the Volume Up key until apple logo appears, dims, and screen off, you will notice your phone boot up in substrate-disabled mode. Proceed to backup your phone with iTunes.