Why can't I add a contact to my Lumia 640 xl?

[Windows Central Question]

the people app opens then close immediately
ive also lost all my contact numbers will my phone was upgraded to windows ten

 

[T Moore]

Windows 10 Mobile is not an upgrade, it is software under development.
There is no fix for specific problems. Reset your phone.
If that doesn't fix it roll back to 8.1

 

[xandros9]

Check people.live.com or whatever contact syncing thing you use (like Gmail, Exchange...)