Know-How Exchange : Social Media

I do work for a non-profit with a pretty good size Twitter following. A former Communications Director (6 plus years ago) absconded with the Twitter password). Password reset has not been possible because he used a personal cell phone and email address for password recovery. Currently, we are able to post via MailChimp as the link was set up before the password was "lost," but there is no access to the Twitter page itself. Twitter says there is nothing they can do for us. We don't want to start from scratch with a new page and lose all those followers. Any workaround suggestions or someplace we could turn to for help?