Your account was more than likely deleted in March, during a pruning of inactive accounts. Your last login was in December. In January it was eligible for suspension and then by February it was eligible for deletion. It was deleted in March, then x10 started restoring users under a one-time-only policy because reminder emails were disrupted during the transition. That ended a few weeks ago. If your account is restored, please don't rely on emails as they can be sent to the spam folder or even blocked. The login requirement is once every 30 days (not once a month). Only logins to https://x10hosting.com/sso/main count. FTP and forum logins do not count.
I'm asking an admin to see if they can restore your account even though the restore timeframe has ended.
I advice you to not rely on email as your sole reminder to login, it has been known to end up in spam folders for some as well. In my opinion it is also wise to login a bit more often then once a month, as a means to keep yourself informed about upcoming changes.