Can't login to game

Hello, 
For a few months now, I've not been able to login to minecraft on my tablet. For a long time prior to this, I was logged in without any issues, but one day it had logged me off. Now after this, when I click log on, it simply closes down the app. It will do so every single time. I've uninstalled/reinstalled the game several times and have even reset my tablet to factory settings. 
I'm frustrated as I have bought stuff and I frequently play this game with my children, and not being logged in, results in not being able to play with them when they aren't home. 
And not an easy game on phone where I'm able to log in
Please help. 
Sincerely 
Denice Milton