lost contacts and cannot add new ones on Win 10 upgrade

[Martin Franklin]

After upgrading to windows 10 from 8.1 on my Lumia 640 I lost all my contacts and can no longer add new contacts and cannot add events to the calendar. 1 update done but still not working.
Any advise appreciated

Update: Problem has been resolved.
I had to add my Hotmail account under other and not Microsoft Accounts. It's now in both but my contacts have returned.