Second Email is Disabled

Our account has two emails associated with it...  the first and primary email is the family email, the second is my personal email. 

Yesterday I noticed that I couldn't access my personal email (the warning icon next to my account name said "There is a problem with this account." - when I click the icon and then click on "Accounts" it states that my personal email "Account is disabled."

I have no idea why this happened and there's no help that I can find to re-enable (and/or access) this account.

How do I access (and re-enable) this email account (which I use daily)?

Thanks!

John.