My name isXXXXX to Justanswer.
I would like to help resolve your problem for you.
Could you have a re-boot of the PC, sometimes this can resolve the problem,
If you cannot update, then delete the old update first.
Open the folder that has the update in it and delete it.
Restart Itunes and connect the phone, Choose Restore
This should re-download the update and fix the phone back to factory settings
at which point you can sync and get your settings back.
I hope this resolves the problem for you