Accounts Gone after Update to W10M

Yesterday night, I happily updated my Lumia 930 to W10M. BIG MISTAKE!
This is my company phone - hence a work tool that supposed to WORK.

After the installation, all account configurations were gone!
Is there a rational reason for that?
Can these accounts be recovered?
The Exchange Client for some reasons no longer works with Google Apps accounts. WHY?

Did you hard reset after update? If not try that. Also, do not restore your phone and apps, instead start clean, reinstall them all one by one. Yup, it's a slow processes, but many people say it's the best way.