Sorry for the trouble. Monetization can be disabled for several reasons. Here's more about it and what to do to turn monetization back on: https://goo.gl/cNar2n . Hope this gets resolved.
We review all applications carefully–if you weren’t accepted into YPP at this time then check your Monetization page in Creator Studio for more info: https://www.youtube.com/account_monetization …. You can make any changes based on those details and always reapply after 30 days.