Your account was probably hacked and used for something that broke the rules. I got an email warning of someone trying to change my password within a week of making an account.
Twitter would be a lot more credible (although anything times zero is still zero) if they didn't have the checkbox "Let people who have your phone number find and connect with you on Twitter" on their "security" lockout verification page.
And, somehow, Twitter keeps spamming my email address in spite of my account having been "locked".
Sorry ... not sorry. No phone number for you.