Unable to sign into any Microsoft account and Edge browser app has disappeared

[Ajdavis]

Lumia 950
OS build 10.0.14915.1000
Version 1607
The device is a pre owned bought from Game unlocked. Have a new Sim from Sky. Calls and texts are all ok but could not use data.Have set up sim with the help from Sky but with no joy. Have hard reset phone but now it is even worse. Can no longer sign in to any Microsoft account eg. Outlook, Xbox etc. and the Edge browser app has disappeared.
When trying to sign in tap add account and choose outlook just goes back to add account. Xbox sign in just sends me back to the initial Xbox page. One drive tap sign in and it sends me back to the Start screen
Any help would be appreciated thanks

 

[HoosierDaddy]

If you haven't used WDRT, start there. It might not fix the problem but it is the only way to be sure the problem isn't from a corruption of or hack of what is used for the hard resets. First thing I would do with ANY used phone even if there are no noticeable problems.