Help please - emails deleted by accident - still showing huge storage though!?

Hello, i've managed accidentally to delete all emails from my email server, every single one... from the "manage disk space" section on roundcube where our emails are. We use outlook for day to day but come onto webmail to check our usage and delete emails where necessary. 1. Is there anyway via cPanel or Outlook to recover these emails? 2. Every folder is totally empty, but cPanel usage is showing as 7.6GB? If they have deleted every email why is there still 7.6GB in there? Thanks