Hi there, monetization can be disabled for several reasons. Here's more about it and what to do if it was an error: https://goo.gl/cNar2n . Also, could you try checking the Spam/Junk folder to see if you're able to locate the email? Keep us posted.
Hmm, could you check your spam/junk folder? Also, the best place to check is your Monetization page in Creator Studio: https://www.youtube.com/account_monetization …. From there, you’ll see an explanation. You’ll also see the option to reapply from that page in 30 days.