If you can no longer connect to the game after a device reset from your Windows 10 Phone, please use the official Windows Device Recovery Tool to fix it.
Note that it is a known issue with Windows 10 Phone that sometime, the Reset option on the device will not reset the device properly and cause software problems. When that happens, please download the official Windows Device Recovery Tool on your PC and use it to fix software problems on your phone.
The download link and detailed instruction can be found on this page: