Failed update, how to fix?

I finally got my wife to update her Lumia640 to Windows 10 Mobile. She is a nester and was very weary of updating, worried it would be too big a change. Sadly: apparently there were errors, as many features do not work. None of her existing text messages or contacts carried over. I cannot add a new contact. I cannot add her outlook account to her outlook account list (her pop and school gmail account came in fine).
How can I fix this?
My son has the exact same phone, and he had no problems updating to Windows 10 mobile.

from Windows Central Forums http://ift.tt/2w2YNx1
via IFTTT