How to allow users who have cancelled their accounts to re-activate / re-enable them? If a user cancels their account on a Drupal 7 site, is there a way to allow them to re-activate their account without requiring administrator intervention?

If a user has second thoughts and wants to rejoin the site using the same e-mail address, I would like to make it easy for them.  I have set the Account cancellation method to Disable the account but keep the content.
There are two URL which can help you in achieving this. First you will have to use Advance User module &amp; then you can extends some hooks of it according to your need for account re-activation.
There is a blog written on similar issue which may help you - Enable/Disable User.

I hope you find your solution.